UK Home Secretary says London bombings linked- expecting more attacks in London
Ongoing search for more Al Qaeda sleepers is race against time
Clarke believes bombings linked
It would be "very, very surprising" if the two sets of London bombings in July were not connected, Home Secretary Charles Clarke has told the BBC.
But Mr Clarke said there was "not a direct linkage formally established".
His comments come after he said on Monday he remained "worried" about the possibility of further attacks.
That followed talks with Met Chief Sir Ian Blair, who has said the fact there were two attacks made further bombs "more, rather than less" likely.
Mr Clarke said despite police progress the risk of terrorism remained.
On the two groups of bombers, he told BBC Radio 4's Today programme: "I think it would be very, very surprising if they weren't linked in some way, but evidence is an issue.
Mr Clarke added that police and security services were working to establish what support and, training and other assistance from outside was being investigated.
Earlier Mr Clarke said he was "absolutely impressed" with the work of the Metropolitan Police since the bombings, saying real progress had been made.
But he said the risk of further terror attacks remained and was being dealt with.
"We remain worried. The commissioner has been very clear throughout that it would be ridiculous for us to assume that a further act would not take place.
"Obviously, one of the main purposes of the investigation - which is rolling ahead very strongly at the moment - is to identify any linkages which would help us act more effectively to be able to reduce that likelihood - and that work is happening," Mr Clarke said.
"The police, together with the other security services, are doing an excellent job.
"But it would be absolutely foolish for me, or for anybody else to say that we've eliminated the risk. We haven't.
"The risk needs to be contested and that's what we're doing."
Mr Clarke made clear there was no intelligence available of any specific threat of a new terrorist attack.
"But we are working on the basis that the people who organised these attacks could proceed with other attacks as well.
"And that seems to me the only rational basis on which we should proceed."
Metropolitan Police chief Sir Ian said: "The fact that there's been two attacks makes it more, rather than less likely that there'll be further attacks.
"I mean, that's just the logic of all this, but we of course are working incredibly hard with the intelligence services to prevent it".
Asked about his plan to deport 10 people deemed to be a threat to national security, Mr Clarke said he wanted the legal process to take as "little time as possible".
"Those individuals concerned are now under detention, pending deportation, and that means they are removed from any particular ability to threaten us in that way. That is a very important step."
His comments came as New York-based Human Rights Watch said the UK could not legally deport suspects such as radical cleric Abu Qatada to Jordan despite a promise they will not be tortured.
The civil rights group says it would be breaking international law if the UK deports suspects to a country where torture is a "serious risk".Story from BBC NEWS: