* Euro depreciation seen helpful to euro zone problems
* China stocking up on copper amid commodity speculation
* WTO agreement could provide needed trade stimulus
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GENEVA, May 28 (Reuters) - The euro's depreciation is no cause for alarm, and will help solve the credit squeeze in the euro zone, the head of the U.N. Conference on Trade and Development (UNCTAD) said on Friday.
"I think this is a natural trend," UNCTAD Secretary-General Supachai Panitchpakdi told reporters in Geneva. "This is something that will help solve the problems of the euro zone."
The UNCTAD chief also said China was stocking up on copper to get ahead of commodity speculators and said he expected the price of minerals and other raw materials to remain volatile, causing strains on both importers and exporters.
Supachai, who formerly led the World Trade Organisation, said it was unlikely that G20 leaders would again call for a quick completion of the Doha Round, given their previous appeals for a tariff-slashing agreement had little effect.
"This has created some kind of loss of credibility," he said, urging countries instead to empower their negotiators to make the concessions needed to reach the global accord that the WTO has been struggling to clinch since 2001.
"Eventually people will be driven back to the negotiating table because of the fact that we need to have stimulus in trade," Supachai said, adding it may be necessary to "calibrate" expectations on big emerging economies such as India for the deal to be palatable to all. (Reporting by Laura MacInnis; editing by Jason Webb/Mike Peacock)