In comments made during the company’s annual general meeting in Switzerland, Mr Glasenberg said many commodities prices are down largely because other mining companies have over-produced relative to demand. The CEO has been critical of iron ore producers for continuing to ramp up production of the steelmaking ingredient even as demand from China tapers off.

“I’m doing my level best to convince my competitors that we should understand demand and supply,” Mr Glasenberg said. Glencore’s shares, which are up 2 per cent this year, have shed 5 per cent in the last 12 months.

While Glencore doesn’t produce iron ore, it is the world’s largest supplier of seaborne thermal coal, which has declined sharply in recent years as production has ramped higher. The mining giant, in response to the price decline in coal, has curbed production at coal mines in Australia and South Africa. Mr Glasenberg said he thinks coal “looks good going forward” in part due to increased demand in Indonesia.

He said he expects copper supplies, which account for about 40 per cent of Glencore’s mining sales, to move into a “deficit” in the near term, in part due to declining ore grades in South America.

Mr Glasenberg, in response to complaints from union officials about how the company is handling a long-running worker dispute at its Sherwin Alumina operation in Texas, said that operation “is not very profitable” because of weak aluminium prices.

Union officials and workers travelled to Switzerland to complain about a months-long lockout of about 450 workers. They said Glencore isn’t treating the workers fairly and that the lockout is hurting Glencore’s profits. Mr Glasenberg said he can’t make any commitments about an agreement with the union and that “these great profits you talk about … it ain’t so good.”

Glencore officials also fielded several complaints about the company’s coal-production facilities in Colombia, including allegations that it is mistreating its workers and harming the environment. Glencore Chairman Tony Hayward said at the meeting that the company’s Colombia coal mines are “a world-class operation engaged in world-class community engagement.”