A suicide bomber who blew himself up in Stockholm at the weekend was carrying a cocktail of explosives and probably meant to wreak carnage among Christmas shoppers, investigators said Monday.

As police searched the father-of-three's home near London, Sweden's chief prosecutor confirmed investigators believed the bomber was a Swedish citizen who now lived in Britain, and was bent on killing "as many people as possible".

After an Islamist group said Taymour Abdelwahab targeted Sweden on Saturday over its military presence in Afghanistan, prosecution chief Tomas Lindstrand warned the bomber would likely have had accomplices.

While the results of DNA tests are still needed for confirmation, Lindstrand told reporters he was "98 percent" certain of the bomber's identity but was trying to work out his eventual target before he blew himself up prematurely.

"He had a bomb belt on him, he had a backpack with a bomb and he was carrying an object that has been compared to a pressure cooker. If it had all blown up at the same time, it would have been very powerful," he said.

"Where he was headed ... we don't know. It is likely that something happened, that he made some kind of mistake that led to part of the bombs he was carrying went off and caused his death.

"This was during Christmas shopping in central Stockholm and he was extremely well-equipped when it came to bomb material ... It is not much of a stretch to say he was going to a place with as many people as possible."

Lindstrand said the bomber might have been headed to the capital's central train station or to Aahlens, a popular department store.

While it had been established the suspect carried out the attack alone, investigators "have to assume he worked with several people," Lindstrand told AFP.

Abdelwahab, who would have been 29 the day after the blasts, was reportedly born in Iraq but, according to investigators, he became a Swedish citizen 18 years and had never come to the attention of the security services.

In London, a spokesman for the city's Metropolitan Police said officers raided a property in nearby Luton late Sunday as part of the probe.

British media reported that Abdelwahab had studied at the University of Bedfordshire in Luton and had been living in the town in recent years.

His wife and children were reportedly still living in Luton, The Daily Mail and The Daily Telegraph reported.

"Officers executed a search warrant under the Terrorism Act 2000 at an address in Bedfordshire. There have been no arrests," said a spokesman.

"We are confirming that this is in connection with the incident in Stockholm on Saturday."

Luton has been a focal point of clashes between Islamic extremists and far-right extremists in recent years.

In 2009, Muslim extremists demonstrated there at a homecoming march for British soldiers, holding placards calling them "Butchers of Basra" and "cowards, killers, extremists".

An Islamist website, Shumukh al-Islam, posted a purported will by Abdelwahab which said he was fulfilling a threat by Al-Qaeda in Iraq to attack Sweden.

On Saturday, Sweden's Saepo intelligence agency and the TT news agency received an email with audio files in which a man is heard saying: "all hidden mujaheddin in Europe, and especially in Sweden, it is now the time to fight back."

Malena Rembe, an analyst for Saepo, told Swedish radio on Monday that it was now believed the voice was that of the bomber.

His message referred to the Swedish army's presence in Afghanistan and to Swedish artist Lars Vilks, the object of constant threats since his drawing of the Prophet Mohammed was first published in 2007.

Saturday's bombings were seen by the Swedish media as a wake-up call and evidence that the country is now the target of international terrorism.

"Openness under attack," Aftonbladet titled on its editorial page while the daily Dagens Nyheter described Saturday's events as "an attack on us all."