Glencore has been waiting for several months for China, the biggest buyer of the materials it trades and mines, to give the go-ahead before it can complete its $35 billion acquisition of miner Xstrata, the largest deal in the sector to date.

Glencore said on Tuesday it had held constructive discussions with China's Ministry of Commerce, or MOFCOM, but that it had pushed the deadline date back to May 2 because it did not expect to have the final approval in time for its previous deadline of April 16.

The merger date has been pushed back several times, with Glencore saying in March that MOFCOM was focusing its attention on copper.

MOFCOM is the only one of the world's main watchdogs to take national industrial policy into consideration in its decisions.

"Glencore believes that it has had constructive discussions with the Ministry of Commerce of the People's Republic of China (MOFCOM) and that these discussions are now in their final stages," the group said in a statement.

"However, Glencore does not expect to receive the final decision from MOFCOM in time for the merger to be completed by 16 April 2013."

(Reporting by Kate Holton, editing by Paul Sandle and Rosalba O'Brien)

Stocks treated in this article : Glencore International Plc, Xstrata PLC