Suspicious sleepovers, naked beach games and public holding of hands: is it true love for Günter Verheugen, the most powerful German in Brussels, or simply a creative new approach to shaping EU industrial strategy? And has he been bending the rules?

Mr Verheugen, Vice-President of the European Commission, says that everything is above board but pressure was piling on him last night to come clean about his relationship to his chief of staff – or to step down.

Photographs, taken furtively through a rose bush, show the stooped figure of the Commissioner entering the house of Petra Erler, his 48-year-old chef du cabinet. A second photograph shows him leaving the Brussels flat the next morning with Ms Erler. Mr Verheugen is taking legal action against Bunte, the glossy magazine that published both pictures this week.

The accusation against the Commissioner is that he promoted Ms Erler – a skilled bureaucrat and one of the few East Germans at the upper levels of the Commission – while conducting an affair with her. This he has been vehemently denying for the past nine months. “There was no relationship beyond friendship at the time of the promotion,” Mr Verheugen said in October. “And that remains the situation today.”

With unusual diligence the German press has been in dogged pursuit. Now the scandal is already being described as the European Union’s equivalent to the Paul Wolfowitz affair – a reference to the head of the World Bank who was forced to step down after giving favourable treatment to his girlfriend.

Above all, it is an embarrassment to Angela Merkel, the German Chancellor, as she enters the most critical stage of the German presidency of the European Union – the preparation of the final summit that is supposed to set the terms of any future European constitutional treaty. Mr Verheugen is not only deputy to José Manuel Barroso, the Commision chief, but also Commissioner for Enterprise and Industry and, as such, the Chancellor’s key German placeman in Brussels.

Yet it is Ms Merkel’s political allies who are baying for Mr Verheugen’s blood. “Mr Verheugen has failed to shake off the suspicion of favouritism,” said Markus Ferber, chairman of the Christian Social Union group in the European Parliament. “Quite the opposite: there is new evidence. Mr Wolfowitz resigned as president of the World Bank for similar reasons. Mr Verheugen should follow suit.”

It should have been easy enough for Mr Verheugen to shrug off the accusations. The couple could, after all, have been engaged in a late-night working session. The Bunte headline, “Power and Love”, admittedly hinted at a different agenda. But it comes after photographs last summer showed the couple holding hands on holiday in Lithuania. Mr Verheugen argued that it was perfectly normal to hold hands with a colleague. His second wife, Gabriele, said that she had known about the holiday in advance. Ms Erler is also married.

Then came photographs of the two colleagues splashing naked on a nudist beach at Nida, on the Baltic coast. The 62-year-old Commissioner was wearing nothing but a red baseball cap. Ms Erler was also naked. Nothing wrong with that, Mr Verheugen’s allies said. Ms Erler grew up in eastern Germany, where attitudes to nudity were very liberal; it was simply a normal collegiate outing.

Mr Verheugen consulted his lawyers and the photographs cannot be reproduced in Germany because they are regarded as a violation of his privacy. Gunther Krichbaum, the designated head of the German parliament’s Europe Committee, said that Mr Verheugen could be in violation of the commission’s Code of Ethics. “This requires that EU commissioners behave in private as well as in public in a manner that is appropriate to the dignity of the office,” he said. “I assume that Günter Verheugen will clear up any doubts about this.”

Herbert Reul, a Christian Democrat member of the European Parliament and Mr Verheugen’s archenemy, said: “Mr Verheugen is damaging his office and the European project. He has to present a comprehensive answer to the accusations against him, or face the consequences.”

Merkel’s score

Angela Merkel, the Chancellor, has been hamstrung in her EU six-month presidency by the leadership uncertainty in France and Britain. This has made it impossible so far to achieve the main goal: defining acceptable terms for a future European constitution.

Her main achievements:

— Smooth enlargement
Romanian and Bulgaria joined the EU on January 1

— Greening of Europe
The EU agreed to cut carbon emissions by 20 per cent (based on 1990 figures) by 2020 and to save energy. This has spurred on the G8 climate agenda

— Made the EU sensitive
To needs of citzens, mobile phone roaming charges are to be cut

— Enthused young people
A huge 50th birthday party was staged in Berlin, selling the EU as a political entity

— Edged to constitution
A date has been fixed for a new treaty, June 2009, in time for the European Elections.

The German presidency has failed to make much progress on renewing EU cooperation treaty with Russia

— Energy security a row between Russia and Poland over meat exports is still slowing progress
— Independence for Kosovo Russia is blocking this

Main remaining priority
To consult every EU state about what it is willing to accept as part of a new consitutional treaty

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