Britain's intelligence services were under pressure Saturday to explain their knowledge of two Islamists suspected of hacking a soldier to death in London, amid claims they had tried to recruit one of them.

Michael Adebolajo, 28, and Michael Adebowale, 22 -- who remained under armed guard in hospital after being shot by police at the scene -- were known to the intelligence services but were reportedly assessed as not posing a deadly threat.

It is understood the arrest was not directly linked to the brutal murder of soldier Lee Rigby, who was hacked to death in broad daylight Wednesday outside the Royal Artillery Barracks in Woolwich, southeast London.

Rigby's distraught wife said the family found it hard to accept that the 25-year-old had been killed not in a war zone but on the streets of his own country.