Chief Executive Ivan Glasenberg has criticised competitors such as Anglo-Australian BHP Billiton (>> BHP Billiton Limited) (>> BHP Billiton plc) and Rio Tinto (>> Rio Tinto plc) (>> Rio Tinto Limited) several times for flooding the market with new, low-cost, iron ore supply which critics says has sent prices into a downward spiral.

"The mining sector is suffering a crisis of confidence," he said in a presentation at an investor conference in Barcelona. "Oversupplying markets regardless of demand is damaging the credibility of the industry,"

He said mining had been the worst performing sector over the last twelve months, with commodity prices, share values and credit ratings all impacted. Investment flow has also weakened and was now about $60 billion below its 2012 peak, when the commodity supercycle turned sour, Glasenberg said.

Iron ore, oil, nickel and thermal coal were the hardest hit commodities in the last year. Although Glencore does not have any meaningful exposure to iron ore, it is the world's largest exporter of thermal coal and has significant exposure to nickel and oil.

The company was more optimistic about the prospects for base metals such as copper and aluminium rather than bulk commodities such as iron ore, coal and oil.

It expects 2015 aluminium demand to grow by 7 percent, while it sees demand for thermal coal and oil rise by only 1 percent and for iron ore to shrink by 1 percent this year.

Glencore has pledged that it would not "cannibalise" its own markets by adding to the supply glut and it said in March that its 2015 coal output would fall by around 6 percent on the year after production cuts at some of its operations.

Its first quarter coal output, however, rose by 4 percent from the same period a year ago.

(Editing by Janet Lawrence)

By Silvia Antonioli