* EU probes new "buy China" stimulus measures
* Chinese rules seen as similar to "Buy American" provisions
* Could lead to challenge at World Trade Organisation (Adds details, background, quotes)
By Darren Ennis
BRUSSELS, June 17 (Reuters) - The European Union's trade chief is examining a so-called "buy China" policy adopted by Beijing that may favour Chinese products and restrict trade, the EU's executive arm said on Wednesday.
"We are scrutinising the details of the Chinese guidelines to determine whether they breach World Trade Organisation rules," said a spokesman for the European Commission, which oversees trade policy for the 27-nation bloc.
EU Trade Commissioner Catherine Ashton will follow developments closely and seek further clarification on the Chinese policy, the spokesman said.
A 4 trillion yuan ($585 billion) Chinese stimulus package requires government-backed projects to seek explicit permission from Beijing before buying foreign goods and services.
"Only Chinese products and services may be used for government procurement, except when certain products or services are not available within the country or could not be bought on reasonable commercial terms," the Chinese directive says.
The EU is concerned the new regulations may hinder European companies and foreign investors in China.
"It smells a lot like the 'Buy American' plan which the EU and, ironically China along with others opposed vehemently," an EU official familiar with the Commission investigation told Reuters.
He was referring to attempts by the U.S. Congress to insert "Buy American" clauses for iron and steel into a U.S. stimulus package. After threats of action against the United States at the WTO, the global trade watchdog, Washington backed down.
Brussels could mount a case against China at the WTO if it judges that the new provisions distort trade or create a barrier to investment by European companies. (Additional reporting by Jeremy Smith; Editing by Dale Hudson)