One of the most profitable years on record for miners is emboldening lawmakers to seek a larger share of their earnings, a move that companies and analysts warn could deter future investment and prolong some expected commodity shortages.

Prices of materials such as copper and iron ore have risen to record highs this year while the countries that produce them are grappling with mounting debts from their economic responses to the Covid-19 pandemic. Those trends have encouraged some lawmakers to reopen talks on how much governments deserve from the extraction of natural resources, mirroring efforts a decade ago when commodity prices ran hot on a boom in Chinese demand.

Companies warn that increased mining taxes or royalties—payments usually tied to production, sales or profits—will deter new investments, which might hurt future supplies of key metals and keep prices higher. Lawmakers point to the large profits being made by mining giants and the billions of dollars that they are sharing with their shareholders.

In copper-rich Peru, Pedro Castillo vowed to increase taxes on miners he accused of plundering the country’s natural resources if his victory in the presidential election last month is confirmed.

Supporters of Pedro Castillo in Lima, Peru, last month. Mr. Castillo is waiting on confirmation of his victory in the recent presidential election.

Supporters of Pedro Castillo in Lima, Peru, last month. Mr. Castillo is waiting on confirmation of his victory in the recent presidential election.

Photo: EPA/Shutterstock

In neighboring Chile, lawmakers are already debating significantly higher mining royalties. A bill before Chile’s Senate proposes a revenue-based, sliding-scale royalty as high as 75% on copper production to help pay for social programs during the pandemic. Today, miners pay a royalty of up to 14% of profits. A local mining lobby called the proposed rates akin to expropriation.

Chile accounts for almost a third of the world’s exports of copper, and Peru roughly 12%. They are the two biggest exporters of copper, meaning that large new taxes could bump up the cost of products, including many that are central to the energy transition such as electric vehicles or wind turbines.

CRU Group, a commodities consulting firm, estimates production from existing copper mines will peak in 2023, with a shortfall emerging in the middle of the decade and deepening, unless new projects advance.

Miners argue that higher taxes can make operations too costly and expansions less likely to happen. Still, those companies might have limited options for investment given the scarcity of deposits of some commodities, such as copper, that can be produced profitably.

A recent PricewaterhouseCoopers survey found 39% of metals and mining CEOs were extremely concerned about tax policy uncertainty, double the 18% result from a poll last year.

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Mining companies have thrived during the pandemic and were bestowed essential-service status during times of heavy restrictions in many parts of the world, while governments now face rising debt levels because of stimulus packages and weakened tax revenue from some other industries, said Paul Bendall, global mining leader at PwC in Australia.

The world’s top 40 miners should report a combined net profit of roughly $118 billion in 2021—up from $70 billion in 2020 and $61 billion in 2019—which would make it one of the highest results on record, according to PwC. 

In Nevada, a new tax on gold and silver mines was signed into law last month and became effective July 1. The Nevada Mining Association expects it will roughly double what miners contribute to state coffers, depending on commodity prices. Proceeds are earmarked for public schools as Nevada—where the pandemic last year closed casinos and hindered tourism—navigates its way out of the pandemic.

“We consider this to be an investment in being part of the new Nevada, but our operations will change, there’s no question about that,” said Tyre Gray, president of the mining association. 

“These dollars just don’t come out of thin air,” Mr. Gray said. “An allocation of one dollar toward taxes is an allocation of a dollar away from something else.”

In Russia, temporary export duties to be imposed on steel and base metals including nickel and aluminum are a bid to bring hot inflation, tied to globally higher commodity prices, under control. The levies will be in place from Aug. 1 through the end of the year.

“ ‘An allocation of one dollar toward taxes is an allocation of a dollar away from something else.’ ”

— Tyre Gray, Nevada Mining Association

“The introduction of duties is not a punishment for metallurgists,” said Russia’s First Deputy Prime Minister Andrei Belousov. “We must protect our internal consumer from what is happening now in the global markets.”

The duties will cost Norilsk Nickel —one of the world’s biggest nickel miners—roughly $500 million, the company’s president, Vladimir Potanin, told reporters in late June. 

Government debt among advanced economies has soared to levels not seen since World War II. Across the developing world, the pandemic is reversing decades of progress in alleviating global poverty as governments are unable to afford sustained stimulus measures.

Peru’s Mr. Castillo previously said he wanted to tax mining profits at 70%, although his economic adviser, Pedro Francke, has sought to assuage investor concerns about his far-left policies and said tax reform would be negotiated with miners. 

Liquid gold being poured to form bars. In Nevada, a new tax on gold and silver mines became effective this month.

Liquid gold being poured to form bars. In Nevada, a new tax on gold and silver mines became effective this month.

Photo: rick wilking/Reuters

What will result “will likely be a gradual tax depending on [metal] prices,” said Mr. Francke, a former World Bank economist. 

Some Peruvian mining executives say any tax increases might hamper new projects, which could undercut future government tax revenue.

“We have to be very careful if we want to be competitive in attracting investment,” said Roque Benavides, chairman of Peruvian mining company Compañia de Minas Buenaventura SA A.

Miners have also cautioned of a potential fallout from the reform proposed in Chile.

“We are concerned about the serious consequences this type of policy may have,” said a spokesman for BHP Group Ltd., which operates the world’s biggest copper mine, Escondida, in Chile’s Atacama Desert. “Chilean mining has an enormous opportunity to take advantage of the forecast increase in global copper demand, but the country must remain competitive in the international market,” he said.

“ ‘We want to have the most [tax] intake without affecting investments.’ ”

— Rodrigo Cerda, Chile’s finance minister

Chile’s Finance Minister Rodrigo Cerda said he expects the tax rates currently proposed will be toned down as the bill makes its way through the Senate. Any watering down of the legislation likely won’t go unchallenged, though, given demands for greater public spending to tackle inequality.

“We want to have the most [tax] intake without affecting investments,” Mr. Cerda said.

—Georgi Kantchev in Moscow contributed to this article.

Write to Rhiannon Hoyle at rhiannon.hoyle@wsj.com and Ryan Dube at ryan.dube@wsj.com