Sarkozy's first cabinet appointment came as no surprise.

Fillon, a 53-year-old senator from the ruling UMP party who worked closely with Sarkozy on his election campaign, has crucial experience in pensions reform which will be a key asset to the new government.

The appointment was announced in a presidential statement a day after Sarkozy took over as head of state from Jacques Chirac. Sarkozy is to announce the rest of his 15-member cabinet lineup on Friday.

Fillon's predecessor, Dominique de Villepin, presented his resignation on Tuesday to Chirac ahead of the handover of power to Sarkozy, who has pledged to carry out deep social and economic reform.

Fillon made his mark as a reformer as social affairs minister under Chirac, from 2002 to 2004, when he carried out an overhaul of France's pension system, facing down million-strong street protests.

Low-key meets high energy

Ironically, in a book in 2006, Fillon had argued for abolishing the post of premier, while advocating a strong presidential-style of rule.

And during the election campaign, Sarkozy himself had said that the premier should only "coordinate the work of the government" and should not share power with the head of state.

Sarkozy's jogging partner throughout the campaign, Fillon has a low-key demeanor that is often described as complementary to Sarkozy's hyper-active style.

Speed was apparently of the essence on Wednesday, when Sarkozy -- in a possibly record-breaking move -- landed in Berlin for his first official state visit, a mere six hours after he was sworn in to office.

'Europe must lose its paralysis'

In Berlin, the new French president met with German Chancellor Angela Merkel, to show his support for strong Franco-German relations and discuss the possibility of reviving the EU constitution.

French and Dutch voters rejected the EU constitution in referendums two years ago. Germany currently holds the rotating presidency of the EU.

"Europe must be shaken from its paralysis as a matter of urgency," Sarkozy said at a joint press conference with Merkel.

Over a working dinner, Sarkozy presented his proposal for a mini-treaty comprising the bare essentials of the failed constitution, to allow the institutions of the 27-nation bloc to function fully.

Sarkozy stressed the importance of maintaining and strengthening the relationship between Germany and France, whose partnership is often described as the driving force behind the EU.

'Sacred' friendship

"I want to say to the German people that the friendship between France and Germany is sacred and that nothing can call it into doubt," he said.

For her part, Merkel thanked Sarkozy for his speedy visit. The gesture made it clear how much the two countries need one another, she said.

Sarkozy said he thinks it is crucial to attack Europe's problems as quickly as possible.

"Waiting too long just makes this more complicated," he said, referring particularly to plans for a new EU constitution. "The first urgent task is to free Europe from its current paralysis."

As for Merkel, she sees Sarkozy as a key partner in her plan to get the EU constitution process going again at the EU summit in June.