By Stephen Brown

STOCKHOLM (Reuters) - A Swedish court has sentenced the self-confessed killer of Foreign Minister Anna Lindh to life in prison, after throwing out a plea of insanity for the 25-year-old man who has blamed "voices" in his head.

"The deed which Mijailo Mijailovic is guilty of warrants a very severe penalty. As no mitigating circumstances have come to light, he is therefore sentenced to life in prison," said the written statement released on Tuesday by the Stockholm court.

The son of Serb immigrants admitted to stabbing 46-year-old mother-of-two Lindh ten times in a frenzied attack in a Stockholm department store last September. Lindh, who had been tipped as the next prime minister, died a day later.

Mijailovic, a high school dropout with no steady job, was arrested two weeks later and confessed in January, telling the court: "I was on my way out but I took a wrong turn. I saw Anna Lindh. Then the voices came and said I should attack her. I could not resist the voices."

But after psychiatrists found he could not be acquitted on grounds of insanity, public prosecutor Agneta Blidberg said in the trial ending last week that the "violent, forceful and aggressive" attack merited a life sentence for murder.

Lindh was Sweden's most popular politician. Her ready smile, stylish blonde hair and black spectacles were high profile in the Social Democrat government's failed campaign for Sweden to adopt the euro in a referendum held three days after she died.

The attack, in a country that has still not solved the assassination of Prime Minister Olof Palme outside a Stockholm cinema in 1986, plunged Sweden into mourning. Red roses piled up outside NK department store and at makeshift shrines in front of euro campaign photos of her on street corners and at bus stops.

Prime Minister Goran Persson called her murder "an attack on our open society". But despite the questions raised about security, politicians in Sweden and other Nordic countries which are also relatively crime-free still rarely have bodyguards.

Defence lawyer Peter Althin has three weeks to lodge an appeal in which he may demand fresh psychiatric tests to prove that his client acted under the influence of anti-depressants and should be freed and get treatment.

Mijailovic, who sought psychiatric help shortly before the attack, was born in Sweden but lived in Serbia with his grandparents for a while as a child. He said he was carrying a knife because he felt threatened and "like a total loser".