Two explosions hit Stockholm on Saturday were a failed terrorist attack which might have caused catastrophic consequences, Swedish Foreign Minister Carl Bildt said on Sunday.

It is "a very worrying attempt of terrorist attack in a crowded part of central Stockholm," Bildt wrote on his twitter.

"It failed, but could have truly disastrous consequences," he added.

Two cars exploded at downtown Stockholm on Saturday, killing one person and injuring two.

The first explosion happened near the Queens street, one of the busiest shopping streets in the city, and the second on an other street only 200 meters away several minutes later, local police said.

One man was killed and another two persons suffered minor injuries.

About ten minutes before the explosions, Swedish news agency TT received an e-mail which blasted the Swedish artist Lars Vilks, who depicted the Prophet Mohammed with the body of a dog. Most Muslims view his caricatures as severely offensive.

The e-mail also warned that the Swedish presence in Afghanistan would draw retaliations against "Sweden and the Swedish people."

"Now your children, daughters and sisters will die like how our brothers, sisters and children are dying," the e-mail said.

"Our actions will speak for themselves, as long as you don't stop your war against Islam, continue degrading the prophet and your stupid support of that pig Vilks," the e-mail added.

The Swedish Security Service SAPO said it also received a similar e-mail. But it couldn't immediately confirm a link to the explosions.

Petra Sjoelander, a police spokeswoman, said the first explosion happened in a car loaded with gas cylinders and that a dead man was found near the site of the second blast.

She said the police did not know whether the two explosions were linked and what caused them.

She added that a police bomb team has been sent to the explosion sites.

Sweden's SVT television later reported the two almost simultaneous explosions were a suicide attack and the dead man was believed to be the bomber. But the information has not been officially confirmed.