BEIJING, Jan. 6 -- Major commodities kept an upward trend on Tuesday, with metals continuing a strong rise. Corn, however, dipped after a week-long price increase following an unprecedented large-volume state purchase.

Corn contracts for May delivery closed 0.77 percent lower at 1,541 yuan (225.3 U.S. dollars) a ton in the Dalian Commodity Exchange. The price was still much higher than the international level.

Corn contracts for March delivery on the Chicago Board of Trade slipped one penny to 4.11 U.S. dollars a bushel on the latest trading day, equal to about 1,107 yuan a ton.

In an effort to encourage corn planting in 2009, the Chinese government announced last month that it would purchase 20 million tons of corn for state reserves from three northeastern provinces known as the country's major grain producers. This came after a previous purchase of 10 million tons.

The news of the state purchase failed to extend price increases, which also reflected sluggish market demand would continue to press the price, analysts said. They expected the price for corn to stay at around 1,500 yuan a tonne during the week.

May Copper on the Shanghai Futures Exchange rose by the daily limit for the third consecutive day on Tuesday, settling at 26,240yuan a lot (five tons). Both zinc and aluminium closed up near their daily limits.

Gold contracts for May delivery dropped 5.4 yuan to close at 184.6 yuan per lot.