A still image taken from a video footage shows a firefighter attempting to put out the fire on a burning car in Stockholm December 11, 2010. [Photo/Agencies]

STOCKHOLM - Two explosions killed a man and injured two people in a busy shopping area in Stockholm on Saturday evening after an email sent to a news agency threatened retaliation for Sweden's military presence in Afghanistan.

Police spokesman Kjell Lindgren said it was possible that the dead man had blown himself up, but this had not been confirmed by investigators. Swedish media reported that he had killed himself with a bomb.

Lindgren said police were also investigating whether other, unexploded bombs were on the scene.

The Swedish news agency TT said it had received an email warning 10 minutes before the blasts, which took place either side of 5 p.m. (1600 GMT), with a threat to Sweden and its people.

It said the threat was linked to Sweden's contribution to the US-led NATO force in Afghanistan, where it has 500 soldiers, mainly in the north.

TT said the warning, which was also sent to Sweden's Security Police (SAPO), also referred to caricatures of the Prophet Mohammad by the Swedish artist Lars Vilks.

The email had sound files in Swedish and Arabic.

"Our actions will speak for themselves, as long as you do not end your war against Islam and humiliation of the Prophet and your stupid support for the pig Vilks," TT quoted a man as saying in one of the recordings.

Vilks depicted the Prophet with the body of a dog in a cartoon in 2007. Most Muslims consider any depiction of the founder of Islam as offensive.

Last March, an American who called herself "JihadJane" was charged with plotting to kill Vilks and using the Internet to enlist co-conspirators. In May, arsonists tried to set fire to Vilks' house.

Gas Cylinders

Police spokeswoman Petra Sjolander said the first explosion had been in a car containing gas cylinders. The dead man was found at the site of the second blast about 300 metres away.

"It looked as if the man had carried something that exploded in his stomach," Pascal, a trained medic, was quoted as saying on the DN.se website. "I removed a Palestinian scarf from his face to free up the airways, but it was too late ....

"He had no injuries to the face or body in general and the shops around were not damaged."

Media reported scenes of panic among teeming Christmas shoppers, with people fleeing amid smoke and the smell of explosives.

Police could not confirm precisely what caused the blasts and investigators and emergency services were at the scene. Witnesses said a bomb disposal robot was being used.

In January, a Somali man was indicted for terrorism and attempted murder for breaking into the home of the Danish cartoonist Kurt Westergaard and threatening him with an axe.

A cartoon by Westergaard in 2005 that depicted the Prophet Mohammad with a turban shaped like a bomb sparked outrage across the Muslim world, with at least 50 people killed in riots in the Middle East, Africa and Asia.