BRUSSELS (Reuters) - The European Commission said it was launching an investigation into claims by a newspaper on Sunday that a senior trade official leaked commercially sensitive information in return for possible reward.

The Sunday Times said Fritz-Harald Wenig, a trade director, had passed the information to undercover reporters posing as lobbyists for a Chinese businessman who wanted to know about secretive anti-dumping investigations.

The Sunday Times said Wenig disclosed information about Chinese candle-making firms likely to be given lenient treatment in an anti-dumping case, and about other cases.

It said he discussed the possibility, proposed by the undercover reporters, of payment or working for the businessman.

But the newspaper also said the question of payment or a job was never decided and Wenig said he would do nothing illegal.

The newspaper quoted him as saying, after the undercover reporting sting was revealed to him, that he had done nothing wrong and information he had passed on was "semi-public".

The Commission said it had opened an investigation to "establish the facts and the appropriate consequences."

"The Commission follows a policy of zero tolerance vis-a-vis unethical and illegal behaviour," it said in a statement.

"At the same time, the Commission recalls and fully respects the presumption of innocence of persons under investigation or subject to allegations," it said.

The Commission's statement was issued late on Friday after it had been told about the story by The Sunday Times.

A Commission spokesman declined to provide any further comment on Sunday.

Wenig's office was not answering calls on Sunday and a Commission spokesman declined to provide his cellphone number.

The European Commission is responsible for investigating whether imports into the 27-nation EU are being "dumped" -- or sold at below their price in the home country or below cost.

The investigations are sensitive because they can lead to the imposition of anti-dumping duties on imports which affect the ability of companies to export to the EU's lucrative market of nearly 500 million consumers.