Three further arrests have been made in connection with the slaying of an off-duty soldier in a street in London on Wednesday.
Counter terrorism officers arrested three men, aged 21, 24 and 28, on Saturday evening on suspicion of conspiracy to commit murder. The BBC reports a Taser was used on two of them.
Drummer Lee Rigby, 25, was run over and then attacked with machetes outside Woolwich Barracks on Wednesday.
Two men arrested on suspicion of murder at the scene are in custody in hospital.
Michael Adebolajo, 28, and Michael Adebowale, 22, were shot by police. They have not yet been charged.
Another man, 29, who was arrested on Thursday on suspicion of conspiracy to murder, has been bailed to return pending further inquiries.
Two women, aged 29 and 31, also arrested on suspicion of conspiracy to murder on Thursday, were released without charge on Friday.
Man arrested after spy claim
Counter-terrorism police arrested a man at the BBC on Friday after an interviewee claimed security services had tried to recruit one of the two suspects in the slaying of a soldier in a street in London.
A man identified by the BBC as Abu Nusaybah said intelligence officers had approached Adebolajo six months ago to see if he would work for them as an informant, but he refused.
Police were waiting to arrest Nusaybah after the interview finished on Friday. The pre-recorded interview was broadcast on Newsnight later that evening.
Drummer Rigby was a veteran of the Afghan war. Two men used a car to run him down outside Woolwich Barracks and then attacked him with a meat cleaver and knives.
The pair told bystanders they were acting in revenge for British wars in Muslim countries.
In the BBC interview, Nusaybah, 31, claimed that intelligence officers visited Adebolajo's London home after the suspect made a trip to Kenya last year.
Nusaybah said his friend had been arrested and questioned in Kenya. This assertion was dismissed by the Kenyan government as a "fairy tale".
"He mentioned initially they (MI5) wanted to ask him if he knew certain individuals," Nusaybah told the BBC.
"But after him saying that he didn't know these individuals, what he said was they asked him if he would be interested in working for them. He refused to work for them."
Asked about Nusaybah's comments, a Home Office spokesman said it never commented on security matters.
A Kenyan government spokesman said it had no record of Adebolajo ever visiting the country.
Prime Minister David Cameron has said a parliamentary committee will investigate the security services' role.