Glencore said on Tuesday it had extended again the date by which it expects to close its merger with Xstrata to May 2, due to the ongoing investigation into the deal in China.

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 did not think it would have received the final approval in time for its previous deadline of April 16.

(Reporting by Kate Holton, editing by Paul Sandle)