One of the suspects in the Woolwich murder case was arrested in Kenya in 2010, the Foreign Office has confirmed.
It said Michael Adebolajo was arrested there and it gave consular assistance "as normal" in the circumstances.
He was believed to have been preparing to fight with Somali militant group al-Shabab, a Kenyan government spokesman told the BBC, and was later deported.
Meanwhile, police investigating soldier Lee Rigby's murder have arrested a 22-year-old man in north London.
The arrest at Highbury Grove, on suspicion of conspiracy to murder, brings the total number made so far in the case to nine.
Several hundred people have gathered at the scene of the murder, some chanting Mr. Rigby's name and waving Help for Heroes flags.
The Met Police said it was aware of a planned community event in which a group of people intended to lay a wreath.
A small group of English Defence League members have also joined the crowd.
The Kenyan government had previously denied that Mr. Adebolajo had ever visited the country, but spokesman Muthui Kariuki said there had been some confusion as he was arrested under a different name.
Mr. Adebolajo was handed over to UK authorities when it emerged he was a British citizen, he added.
In video footage of his court appearance which emerged on Sunday, Mr. Adebolajo is heard to say: "These people are mistreating us, we are innocent."
Islamist insurgent group al-Shabab is affiliated to al-Qaeda and is thought to have 7,000 to 9,000 fighters. It killed 76 people in a double bomb attack in Uganda as they watched the 2010 World Cup.
Mr. Adebolajo, 28, and a second man, Michael Adebowale, 22, were arrested on suspicion of the murder of soldier Lee Rigby in Woolwich on Wednesday.
They remain in custody in hospital in a stable condition after being shot and wounded by police at the scene after the killing.
Three further men, aged 21, 24 and 28, were arrested in London on Saturday evening on suspicion of conspiracy to commit murder — a Taser was used on two of them.
A 29-year-old man arrested earlier on suspicion of conspiracy to murder was released on bail on Saturday, while two women aged 29 and 31, arrested on Thursday, have been released without charge.
The Punch