Anti-terror officer says raid police 'had no choice'.
He refused to disclose what the information related to, when it had been received or whether it had originated from the police or the security service MI5.
However, he said, 'It is very important that I emphasise the police did receive specific intelligence.
'We were left with no choice but to act upon that intelligence. Public safety was our top priority.'
Mr Hayman said the operation had been launched with 'public safety foremost in our minds' but the way in which the raid was carried out was with 'consideration for officers' safety'.
He went on, 'If you have public safety foremost in your mind, time will always be a critical factor.
'Having got the specific intelligence and made the decision, there was no choice but to act upon it. We had no choice but to act upon it quickly.'
Mr Hayman revealed that material had been recovered from the house which he described as 'material consistent with a search of this nature'.
This consisted of documents and computers, he said, but confirmed officers had not yet recovered what the intelligence had suggested they might find.
'We have not found what we went in there to look for,' he admitted.
However Mr Hayman pointed out that the search still had several days to run and was still very much a live investigation. The assistant commissioner, one of the country's most senior anti-terror officers, confirmed the raids last Friday had involved close to 250 police officers. He admitted it had appeared 'high profile and to some, a large number of police officers', but insisted it was necessary. 'If you chose not to do that - and heaven forbid it was the wrong decision and there was some device - you would never be able to live with yourself that you shied away from taking the decision to intervene.' Mr Hayman refused to discuss the circumstances of the shooting which took place during the raid.