Germany sees no grounds to speculate on a possible military intervention in Syria, its foreign minister said Wednesday, a day after France's president said armed force was not ruled out.

"From the federal government's point of view, there is no reason to speculate over military options," Guido Westerwelle was quoted as saying in an interview to appear in Thursday's issue of the Die Welt daily.

Major Western powers said Tuesday they would expel Syria's diplomatic envoys in protest at the weekend massacre in the town of Houla, in which more than 100 people were killed.

The United States, Britain, France, Germany, Italy and Spain as well as Canada, Australia, The Netherlands, Bulgaria, Switzerland and Belgium announced decisions to expel ambassadors or top envoys.

Germany's foreign minister said Saturday he was "horrified" by reports that more than 90 people had been massacred in a Syrian town, and said those responsible must be punished.

"I am shocked and horrified by the news that dozens of civilians, including many children, were killed in attacks by the security forces of the Assad regime," Guido Westerwelle said in a statement.

World powers and Iran hope to lay the groundwork for an end to the long-running crisis over Tehran's nuclear program in talks in Baghdad on Wednesday, but the challenges are immense.

The meeting with the P5+1 -- the United States, China, Russia, Britain, France and Germany -- comes at a time of unprecedented tensions more than three years since Barack Obama became U.S. president promising a new dawn in relations.

Some 20,000 people joined a march through the centre of the German financial capital of Frankfurt Saturday, protesting against European austerity programs, police said.

It was the only demonstration of the anti-capitalist movement known as "Blockupy Frankfurt" that was authorized by the city and justice authorities. The other protests over the past four days had been banned by city officials.

Lightning hit French President Francois Hollande's plane as he flew for Berlin on his first trip abroad as head of state on Tuesday, forcing him to turn back, the defense ministry said.

The presidential Falcon 7X "was hit by lightning" and returned to Villacoublay military airport outside Paris, a defense ministry spokesman told Agence France Presse.

Francois Hollande was sworn in as France's first Socialist president since 1995 on Tuesday at a solemn ceremony overshadowed by the debt crisis threatening to unravel the eurozone.

Hours later Hollande named Jean-Marc Ayrault, the head of the Socialist bloc in parliament and mayor of Nantes, as his prime minister.

Voters in a crucial German state emphatically punished Chancellor Angela Merkel's pro-austerity party Sunday, awarding her main center-left rivals a major boost ahead of 2013 national elections.

While Germans nationally back Merkel and her tough stance on European belt tightening and debt reduction, voters in the bellwether state of North Rhine-Westphalia plumped for the opposition's more growth-oriented approach.

German Chancellor Angela Merkel said Saturday she believes a stable partnership with Socialist French president-elect Francois Hollande is possible after she backed his rival Nicolas Sarkozy.

In answer to a journalist's question to that effect, the conservative leader said: "Yes, I think I can, because we know that... good Franco-German relations are quite simply very important for both countries."

German Chancellor Angela Merkel said Thursday that the timetable laid out by NATO for international troops to withdraw from Afghanistan by the end of 2014 must be respected.

"The principle which applies for the German government is: we entered (Afghanistan) together, we will leave together," she said after comments by French president-elect Francois Hollande that he wanted to pull French troops out this year.