Defence Secretary John Reid and Foreign Secretary Jack Straw all criticised the dossier from Chatham House formerly the Royal Institute of International Affairs. Its report said there was "no doubt" the invasion of Iraq caused particular difficulties for Britain and the wider coalition against terror.
Police are still trying to establish the type of explosives used in the London bombings more than 10 days after the attacks which killed at least 56 people, it emerged last night.
Forensic experts are scrutinising the four blast sites to determine the exact make-up of the substance and to see whether it can be linked to the home-made explosives found at a so-called "bomb factory" at a property in Leeds.
It also emerged yesterday that three of the four suicide bombers in the July 7 attacks travelled to Karachi in southern Pakistan last year.
Pakistani officials said 18-year-old Hasib Hussain who detonated his device on a bus in Tavistock Square arrived a year ago aboard a Saudi plane.
Shahzad Tanweer, 22, the Aldgate tube bomber, and Mohammed Sadiq Khan, 30, who was responsible for the Edgware Road blast, then arrived in Karachi in November aboard a Turkish Airlines flight. Security officials are trying to establish what the three men, who are all from Leeds, did during their visit.
As the investigation continued abroad, new details were released last night about the unprecedented scope of the police inquiry into the bombings.
More than 2,000 police officers have worked on the inquiry so far, with 500 expected to continue as permanent "core" staff. Officers have already analysed 6,000 CCTV tapes, but by the end of the investigation they expect to have collected a total of 25,000, according to the figures.
More than 1,000 witness statements have been taken, 3,500 documents such as letters, phone records and bills have been seized and police are trying to follow up information from 3,500 calls to the Anti-Terrorist hotline.
In another development yesterday, Britain's three major political parties reached agreement in principle to co-operate on fresh anti-terror legislation.
The Chatham House document also claims Britain has suffered as a result of Prime Minister Tony Blair acting as a "pillion passenger" of the United States in the war on terror.
The academics claim, in a joint report with the Economic and Social Research Council, that British troop deployments in Afghanistan and Iraq increased the chances of an attack.
They also insist that the war helped boost recruitment and fund raising for al-Qaida terrorists.
Report authors Frank Gregory, of the University of Southampton, and terrorism expert Professor Paul Wilkinson, of the University of St Andrews, said: "There is no doubt that the situation over Iraq has imposed particular difficulties for the UK, and for the wider coalition against terrorism."
The authors also suggest common al-Qaida tactics are difficult to guard against in Britain.
"In an open society such as the UK it is notoriously difficult to prevent no-warning co-ordinated suicide attacks, the characteristic modus operandi of al-Qaida," the report states.
However, Mr Reid said bombings in Turkey and Iraq since July 7 show terrorism is an international problem.
"The terrorists want to kill anyone who stands in the way of their perverse ideology," he said.
"So when this report says that we have made ourselves more of a target because of our involvement in Afghanistan and Iraq and our efforts to tackle al-Qaida, what alternative it is proposing? That we should stand back while others take on the terrorists?"