Police are checking that no more terror suspects have been allowed to "slip through" in the wake of lapses that allowed a British extremist to skip the country while on bail.
A furore erupted after Abu Rumaysah, who is suspected of murdering five people in an Islamic State video, was able to leave the UK after failing to hand in his passport.
Metropolitan Police Commissioner Sir Bernard Hogan-Howe said the force is checking that all bail conditions placed on suspected terrorists have been pursued "with rigour".
On Tuesday counter-terrorism chief Mark Rowley branded police bail "weak" and "toothless" and said officers are in talks with the Government about introducing tougher powers.
Speaking on Nick Ferrari's show on LBC on Wednesday, Sir Bernard said: "The first thing is we're looking at the law, should that be changed? The second thing is, to provide some reassurance for me, is have we looked at all those other people on bail? If we've asked for passports, whatever we've done, have we pursued every one with rigour in every case? Or have we allowed any to slip through? We're in the process of doing that."
Of around 339 arrests last year, around a third involve suspects who are on bail.
Scotland Yard is investigating how Rumaysah - born a Hindu called Siddhartha Dhar - was able to leave the country in 2014 after being arrested six times.
Sir Bernard said that officers had visited his home, and insisted that a letter sent by police urging him to hand in his passport as part of bail conditions was the final stage of a formal process.
"We are looking at that case to find out exactly how he got out of the country. There are only so many things we can do within the law. They (the officers) did those things.
"I can only reassure you that (the letter) was not the only thing they did. The letter was the very final point of a formal process."
When asked if officers had visited Rumaysah's home, he said: "I'm sure, yes."
The suspect left the UK with his family the day after being released on bail, travelling to Paris and then Syria.
Prime Minister David Cameron has said he will consider Mr Rowley's call for a change in the law.