Police looking for links

Police officers stand outside a block of flats in Greenwich following a raid in connection with the killing of a British soldier in nearby Woolwich, southeast London, May 23, 2013. [Photo/Agencies]

The two men used a car to run down Drummer Rigby outside Woolwich Barracks in southeast London and then attacked him with a meat cleaver and knives, witnesses said.

The pair told shocked bystanders they acted in revenge for British wars in Muslim countries.

"We swear by almighty Allah we will never stop fighting you. The only reason we have done this is because Muslims are dying every day," Adebolajo was filmed saying by an onlooker. "This British soldier is an eye for an eye, a tooth for a tooth."

Rigby, who had a two-year-old son, was not in uniform. The bandsman was working locally as an army recruiter.

"All he wanted to do from when he was a little boy was to be in the army," his family said in a statement. "He wanted to live life and enjoy himself."

In Nigeria, with a mixed Christian-Muslim population and where the authorities are battling an Islamist insurgency, a government source said there was no evidence the Woolwich suspects were linked to groups in west Africa.

British investigators are looking at information that at least one of the suspects may have had an interest in joining Somalia-based Islamist rebel group al Shabaab, which is allied to al-Qaida, a source with knowledge of the matter said.

Al Shabaab linked the attack to the Boston bombing and last year's gun attacks in the southern French city of Toulouse.

"Toulouse, Boston, Woolwich ... Where next? You just have to grin and bear it, it's inevitable. A case of the chickens coming home to roost!" the rebels said on Twitter.

Peter Clarke, who led the investigation into the 2005 bombings, popularly known as 7/7, said that if the Woolwich attackers did turn out to be acting alone, it showed the difficulty the security services faced in trying to stop them.

"An attack like this doesn't need sophisticated fund raising and sophisticated communications or planning," he told Reuters. "It can be organized and then actually delivered in a moment."