Up to 18 people were feared killed Monday in one of Germany's worst road accidents after a tour bus carrying pensioners burst into flames in a collision with a trailer truck, police said.

"Thirty passengers were taken to hospitals, some with serious injuries. The others are believed to have died in the burning tour bus," which had been carrying 48 people, police said in a statement.

The bus carrying 46 passengers and two drivers rammed into the trailer in a traffic jam on the motorway A9 close to the Bavarian town of Stammbach.

The crash shortly after 7 am (0500 GMT) sent the bus up in flames, with television images showing only the charred skeleton of the vehicle remaining.

The bus was carrying a tour group from eastern Germany's Saxony state, police said, and it was bound for Nuremberg, according to Bild newspaper.

Chancellor Angela Merkel voiced "great dismay" over the crash, with her spokesman saying: "Our thoughts and condolences go to the victims and their family members, as well as to the injured. We hope that those who have been rescued will recover from their injuries."

Transport Minister Alexander Dobrindt and Bavaria state's interior minister Joachim Herrmann were on the way to the site. 

The accident struck near the southern town Bayreuth, best known for the opera festival that draws thousands of classical music lovers every summer.

- Flown to hospital -

The region close to the Czech border is also dotted with spas and castles, and the A9 is a trunk motorway leading to many popular summer holiday spots.

Some 200 emergency workers were deployed to the site, including firefighters, rescue workers and police, while south-bound traffic on the motorway remained blocked.

Those hurt were being flown by rescue helicopters to hospitals, many with life-threatening injuries.

With the likely toll, the accident at the start of the summer holiday season is one of the worst to hit Germany.

Among the deadliest in recent years was a collision in June 2007, when 13 people were killed as their tour bus drove off the road and plunged several metres down a slope in eastern Germany's Saxony-Anhalt state.

In September 1992, 21 people died when a bus swerved out of its lane and struck a truck before ramming into the road divider in the southern Black Forest region, a key tourist destination.

Across Europe, the last such fatal accident struck on January 21 in Italy, when an accident involving a Hungarian bus carrying teenagers left 16 dead.

In France, a head-on crash in October 2015 between a truck and a bus carrying pensioners claimed 43 lives as both vehicles burst into flames.

Source: AFP