Police received email referring to Afghanistan and artist minutes before Stockholm blast

The Swedish news agency TT said it had received an email warning with a threat to Sweden and its people ahead of the explosions. It said the threat was linked to Sweden's presence in Afghanistan, where it has a force of 500 soldiers, mainly in the north.

TT said the warning, which was also sent to Sweden's Security Police (SAPO), was received 10 minutes before the blasts, and also referred to caricatures of the Prophet Mohammed by 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 sound files.

Police said the first explosion had been in a car containing gas canisters. The dead man was found at the site of the second blast about 300 metres away. It was not immediately clear precisely what caused the blasts and investigators and emergency services were at the scene.

In May this year Vilks, who depicted the Prophet Mohammed with the body of a dog in 2007, suffered a failed arson attack on his house, but was not home when it happened.

He said people smashed windows at his house in the small town of Nyhamnslage in southwest Sweden and tried to light petrol which they threw inside. But the attack resulted only in minor damage in the kitchen and on the facade of the house.

"I have had several threats and phone calls. It is this kind of mob that is acting and in this mob there are elements who are ready to take physical action. They have never before attacked my home, I have always thought that that was off-limits. But now that has happened and it is several borders that have been crossed," Vilks said after the attack.

Vilks said the aim of his drawing had been to further freedom of expression.

"This should be a small thing, really. To insult a religion. You cannot make any exceptions for religion, I mean, that's the point. It should be the same rules as we have for Christianity or the Jewish religion or whatsoever. That we should make an exception - Islam is no more holy than the other ones," the artist said.

But most Muslims consider any depiction of the founder of Islam as offensive.

Only a few weeks before the arson attack, Vilks was assaulted by a man during a lecture after he started showing a video about homosexuality and religion, particularly Islam.

In March an American who called herself "Jihad Jane" was charged with plotting to kill the Swede and using the Internet to enlist co-conspirators.