The EU's top competition regulator has opened an investigation into a proposed online advertising tie-up between Google and Yahoo.
'We are looking at whether the merger may have some anti-competitive effects in the European area,' said a spokesman for EU Competition Commissioner Neelie Kroes.
'We don't know whether there is a problem; we are looking at it in case there is,' he added.
Google and Yahoo say the deal is limited to web properties in the US and Canada but Google has said there is potential to extend it to other parts of the world.
The World Association of Newspapers is asking competition authorities in both North America and Europe to block the advertising deal on anti-competitive grounds.
The Paris-based association said the deal would have a negative impact on the advertising revenues that the search giants provide to newspaper and other websites, and on the cost of paid search advertising.
The EU spokesman said that the authority is receiving cooperation from both companies in the Brussels probe.
The enquiry is similar to one which the US Department of Justice launched in July to ascertain whether the deal would stifle competition.
Companies found to be in breach of EU competition rules may face fines equalling up to 10% of their revenues.
