CORRECTED - CORRECTED-BASF China cracker submits feasibility for approval

(corrects in last paragraph to 140-year from 14-year)

BEIJING, March 18 (Reuters) - German chemical giant BASF (BASF.DE) and partner Sinopec Corp (0386.HK) have submitted feasibility studies for a planned $900 million expansion for their China cracker, companies said on Tuesday.

Under the expansion plan first announced in July 2006, the steam cracker, in eastern Chinese city of Nanjing, will add 25 percent or 150,000 tonnes per year capacity by end of 2010, on top of an existing 600,000 tpy plant.

"It's a necessary protocol towards winning government approval -- completion of commercial and technical feasibilities," said a public affairs official with BASF's China operations.

Sinopec said in its online in-house newspaper (www.sinopecnews.com.cn) that downstream units under the same expansion plan will start operation this year, without giving further details.

A steam cracker processes naphtha or natural gas into ethylene, a key building block for plastics, rubber and synthetic fibre.

BASF and Sinopec have poured $2.9 billion into the Nanjing petrochemical complex , the largest single investment in the German company's 140-year history.

(Reporting by Chen Aizhu)

(aizhu.chen@reuters.com; Reuters Messaging: aizhu.chen.reuters.com@reuters.net; +8610 6627 1211)