Britain could reduce its vulnerability to terrorist attacks if it stopped its Muslim minority from retreating to ghettos that become breeding grounds for Islamic extremists, a think tank said Friday.

The report, published by the Royal United Services Institute, said Britain allows such isolated communities to form out of the mistaken belief that it is promoting humanism and multiculturalism.

"One reason that the United States does not suffer from homegrown terrorism is that it is the world's melting pot, where immigrants are Americans, salute the flag, and obey the constitution and the law," Gwyn Prins, one of the report's authors, told The Associated Press.

"The U.K. should have the self-confidence to do the same, but we don't," said Prins, a specialist on international security at the London School of Economics. "We don't insist they learn English, that they fully and properly integrate into our society as a whole. So we have these ghetto societies where Islamist extremists can create a narrative of resentment and recruitment."

British society must respect and permit the beliefs of all immigrants within the law, but it should not allow them to live in isolated communities with more connections to their homeland than to Britain, Prins said.

Britain's long-standing multicultural traditions once gave free reign to immigrant groups such as Muslims when it came to firebrand mosque sermons, street protests, fundraising and head scarves for women. But the government has been putting restrictions in place since Sept. 11, 2001.

Britain, which has about 1.6 million Muslims, has suffered a series of terrorist attacks, some involving Muslim immigrants.

On July 7, 2005, four suicide bombers -- three of them British-born Muslims -- killed 52 people in London.

Two weeks later, four al-Qaida-inspired bomb plotters launched similar, though unsuccessful attacks, on the subway system. The attackers came to Britain as youths from countries in the Horn of Africa. Some are British citizens, others have refugee status.

Last year, an Indian engineer drove a jeep loaded with gas canisters into the passenger terminal at Glasgow Airport in Scotland. He later died of his injuries. An Iraqi doctor, a Jordanian doctor and an Indian doctor were charged with conspiring to cause explosions.

Prime Minister Gordon Brown's government questioned the accuracy of the think tank report.

"The safety and security of our citizens is the government's main priority and the government rejects any suggestion that Britain is a soft touch for terrorists," the government said in a statement.

The RUSI article said a wide range of security risks at home and abroad have left Britain in a "confused and vulnerable condition."

The report says the government lacks a coherent and comprehensive means of analyzing the country's security risks and what should be done to contain them. It says this not only unnerves the public but also leaves Britain looking "like a soft touch."

The RUSI paper urges Britain's government to restore defense and security as top priorities and to create two powerful new government committees made up of senior ministers, legislators and defense chiefs to coordinate the country's security policies.