The continuing debate about the wisdom of Britain's military commitments has intensified after the bombings of three London underground trains and a bus on July 7.
Police on Monday raised the death toll in the attacks to 56, including the four suicide bombers.
The Royal Institute of International Affairs and the Economic and Social Research Council said the situation in Iraq had given "a boost to the al Qaeda network's propaganda, recruitment and fund-raising" and provided an ideal training ground for terrorists.
The government denies that its presence in Iraq influenced the London bombers, reports CBS News Correspondent Elizabeth Palmer.
"The time for excuses for terrorism is over," British Foreign Secretary Jack Straw said at an EU meeting in Brussels, Belgium. "The terrorists have struck across the world, in countries allied with the United States, backing the war in Iraq and in countries which had nothing whatever to do with the war in Iraq."
However, Britain's defense secretary said over the weekend he hopes to in Iraq by almost two-thirds by the middle of next year.
Meanwhile, Palmer reports the branch of the investigation in Pakistan is very active at the moment. Cell phone records as well as travel records suggest that at least two of the young bombers had established links there with established terrorist networks.
Police are still searching homes and businesses in Leeds, including an Islamic bookshop. They want to find out who gave orders to the four young bombers caught here on a surveillance camera just setting out on their deadly mission.
On Sunday, Britain's largest Sunni Muslim group issued a binding religious edict, or fatwa, condemning the suicide bombings as the work of a "perverted ideology."
The Sunni Council said the Quran, the Muslim holy book, forbade suicide attacks.
"Who has given anyone the right to kill others? It is a sin. Anyone who commits suicide will be sent to hell," said Mufti Muhammad Gul Rehman Qadri, the council chairman. "What happened in London can be seen as a sacrilege. It is a sin to take your life or the life of others."
The council said Muslims should not use "atrocities being committed in Palestine and Iraq" to justify attacks.
"We equally condemn those who may have been behind the masterminding of these acts, those who incited these youths in order to further their own perverted ideology," Qadri said.
The Sunday Times reported that one suspected bomber, 30-year-old Mohammad Sidique Khan, was investigated last year by MI5, Britain's domestic intelligence service, but was not regarded as a threat to national security or subsequently put under surveillance.
MI5 began evaluating Khan, a Briton of Pakistani ancestry, during an inquiry that focused on an alleged plot to explode a large truck bomb outside a target in London, the newspaper said.
The Metropolitan Police and a spokesman for Prime Minister Tony Blair declined comment.
The head teacher of Hillside Primary School, which employed Khan as a teaching assistant from March 2001 to December 2004, described him as "hardworking, passionate and dedicated in his work with children."
"All of us at Hillside are utterly shocked to hear that one of our staff had been responsible for such an horrific act," head teacher Sarah Balfour said.