ISLAMABAD, Pakistan -- Three of the four British men identified as the London bombers visited Pakistan this year, two traveling together, Pakistani officials confirmed yesterday. Investigators are trying to determine whether their trips were connected with planning for the attack that killed 56 people.
The information released yesterday adds to suspicions that the three bombers, who all grew up in or around the same neighborhood in Leeds, England, may have received instructions or assistance from militants based in Pakistan and tied to Al Qaeda.
Shahzad Tanweer, 22, and Mohammad Sidique Khan, 30, two of the bombers of Pakistani descent, flew to Karachi on Nov. 19 on a Turkish Airlines flight and remained there until February, Pakistan's Federal Investigation Agency said.
Tanweer, an avid sportsman whose father owned the local fish-and-chips shop, had told his family he was going to Pakistan to study religion.
Investigators are trying to determine whether he and Khan met in Pakistan with Hasib Hussain, 18, another of the suspected bombers who was already there.
Khan, Tanweer, Hussain, and the fourth bomber -- a Jamaican-born Briton named Germaine Lindsay, 19, a convert to radical Islam -- are all thought to have died in the July 7 blasts on three Underground trains and a double-decker bus.
Officials initially believed all four had no previous involvement in terrorism, but authorities have since said that Khan had come to their attention in relation to a plot foiled last year by British detectives who found a large amount of explosive materials in a west London warehouse. Khan was not considered enough of a threat then to be put under full-time surveillance.
British Muslims have appeared in disguise on British television several times over the past year speaking of their desire to become suicide bombers to defend Islam, which they say is under attack from the West.
The existence of extremist preaching has spurred Prime Minister Tony Blair's government to prepare new antiterrorism laws, including a provision that would bar ''indirect incitement" such as praising suicide attacks and acts that prepare for terrorist attacks.
In a show of unity, Home Secretary Charles Clarke met yesterday with opposition Conservative and Liberal Democrat leaders to get a consensus on the new law, expected to be passed when Parliament returns to session in October.
Despite the renewed anti- terrorism efforts, the British government is facing increasing criticism for its security posture before the attacks, with some politicians calling for an inquiry into whether there had been an intelligence failure.
According to The New York Times, the government had lowered its threat assessment by one level less than a month before the bombings based on a confidential terror threat assessment by Britain's top intelligence and law enforcement officials that ''at present there is not a group with both the current intent and the capability to attack" the country.
The Times report cited British officials as saying the reduced threat level had no practical impact on antiterrorism measures. The report said a copy of the assessment by the Joint Terrorist Analysis Center was made available by a ''foreign intelligence service."
Meanwhile, Foreign Secretary Jack Straw responded angrily yesterday to a think tank report suggesting that Britain's participation in the war in Iraq alongside the United States had left the country more vulnerable to terrorists. The report, issued by Chatham House, formerly the Royal Institute for International Affairs, and by the Economic and Social Research Council, said Britain's unequal partnership with the United States had left it vulnerable to attacks.
Straw said it was time to stop making ''excuses" for terrorism. ''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," he said in Brussels.
In Leeds, authorities searched an Islamic bookstore for a fourth day. Residents of the Beeston neighborhood said the Iqra Learning Center had become a meeting place for militant young men. They also continued to search the Leeds home of Egyptian biochemist Magdy El-Nashar, where police say they found explosive materials. Nashar is in custody in Egypt.
Egyptian authorities say Nashar, who was an instructor at the University of Leeds, has denied any involvement in the attacks, although his phone number was found in the mobile telephone of one of the bombers, Hussain.
In Pakistan, immigration records show that Tanweer and Khan stayed in Pakistan for almost three months and departed together on Feb. 8 from Karachi.
Hussain arrived in Karachi from the Saudi capital, Riyadh, on July 15, 2004, Pakistani authorities said. It is not known exactly when he left Pakistan, but he seemed to have returned home to Britain about the same time as the other two.
Pakistani authorities released photographs of the three that were taken when they arrived at Karachi airport. The photos were taken by a US-developed security system installed after the Sept. 11 attacks; it photographs all passengers as they present their passports upon arriving or departing from Pakistani airports.
The Times of London said yesterday that it had been told by unidentified Pakistani security officials that all three men met with known Al Qaeda suspects during their trip and spent most of the time with figures from outlawed militant groups.