(Corrects to say last month of no supply was Feb 2012, not early 2007)
* Normally supplies 30,000-50,000 tonnes crude a month
* Crude part of China aid programme to North
* Not clear is this marks action to punish North for nuclear test
BEIJING, March 21 (Reuters) - China did not export any crude oil to North Korea in February, customs data showed on Thursday, marking the first absence of deliveries since the same month in 2012.
Crude oil is the largest commodity by value that is supplied to North Korea under Beijing's aid programme. It was not immediately clear if the lack of supply represented a unilateral action by China to punish North Korea for its nuclear test on Feb. 12.
Customs data showed the last time China missed monthly supply shipments was in February 2012. There were also no exports in February 2011.
Beijing has always been loath to back harsh sanctions on North Korea, fearing it could lead to upheaval in the poor, unpredictable nation on its border and perhaps even its collapse.
China is Pyongyang's most important diplomatic and economic ally, but relations have been strained by recent bellicose actions by North Korea, including the nuclear test.
China, a permanent U.N. Security Council member with veto power, backed U.N. sanctions, including measures approved on March 7 to impose financial restrictions and crack down on Pyongyang's attempts to ship and receive banned cargo.
Beijing normally supplies between 30,000 to 50,000 tonnes of crude oil to North Korea every month (222,000 to 370,000 barrels). Exports in 2012 totalled 523,041 tonnes, China General Administration of Customs data shows.
At $100 per barrel, China's annual crude oil supplies last year would have been worth about $380 million.
Officials at the Ministry of Commerce were either not aware of the customs figures or declined comment. The ministry is a key agency that oversees the aid programme, which includes supplying commodities such as crude oil and diesel fuel.
Oil trading officials with knowledge of China's oil aid to North Korea told Reuters last week that the ministry had some internal discussions about how to respond following Pyongyang's latest nuclear test.
One of them said there may be "some kind of curb" in supplies but declined to elaborate.
The customs data showed a small quantity of diesel fuel flowed to North Korea in February amounting to about 4,000 tonnes (31,200 barrels). For the whole of 2012 China supplied 31,050 tonnes of diesel and 56,093 tonnes of gasoline to North Korea, customs data shows.
Prior to 2011, China suspended crude sales to North Korea in early 2007 and in September 2006, which also coincided with a nuclear test in October that year. (Reporting by Chen Aizhu; Editing by Neil Fullick)