A candidate for British prime minister said Thursday that the United Kingdom should not be at the "beck and call" of the United States, as the leaders of Britain's top three political parties clashed in their second televised debate.

Nick Clegg, leader of the Liberal Democrats, said during the debate that Britain should act on the world stage in its interests and "not on the beck and call of somebody else," a thinly veiled reference to the U.S.

His comment prompted his Labor Party rival, Prime Minister Gordon Brown, to label him "anti-American."

The Liberal Democrats, traditionally a "third party" in British politics, voted against the war in Iraq, and Mr. Clegg, who has emerged as a strong contender after a polished performance in the first debate last week, has questioned what he calls Britain's "subservience" to U.S. interests.

Thursday's debate in Bristol dealt largely with foreign-policy issues, from Britain's role in Europe to whether the candidates would support future multilateral operations against al Qaeda.

Britons will vote on May 6.

Asked whether Britain would participate in future operations against terrorists, Mr. Brown said that acting against al Qaeda was essential to keeping Britain safe.

"We've already got al Qaeda in Somalia; we've already got problems with al Qaeda in Yemen. We are having to take action with our multilateral partners to deal with these problems and will continue to have to do so," the prime minister said.

He said a "chain of terror" links al Qaeda to acts of violence that could happen in Britain.

Conservative Party leader David Cameron, who has been leading in polls, emphasized the need to learn from "mistakes of the past."

The debate, only the second of its kind to be televised, turned feisty at times. At one point, Mr. Brown chided his opponents, saying they reminded him of his two young sons squabbling at bath time.

But analysts said foreign policy is not a top concern for British voters.

Tony Travers, an elections specialist at the London School of Economics, told The Washington Times that changes of government in Britain rarely alter foreign policy.

"The U.S. remains Britain's most important strategic ally, though Nick Clegg has said he no longer really believes that the U.K.'s relationship with America is 'special,' " Mr. Travers said.

He described the Liberal Democrats as far more "pro-European" than Labor and the Conservatives, one of which he said is likely to be the largest party in a new Parliament and both of which remain "staunchly Atlanticist."

Rhian Chilcott, head of the Washington office of the Confederation of British Industry, said the U.S. and Britain share a special relationship, "but it is a special economic relationship, not a political one."

In March, a panel of British lawmakers said the phrase "special relationship" - coined by Winston Churchill more than six decades ago - no longer reflects political reality and should be dropped.

Still, the top issues in the British elections - immigration and the economy -are similar to those in the U.S.

Mr. Clegg said illegal immigrants should pay their taxes and speak English, while Mr. Cameron contended that immigration to Britain in recent years has "simply been too high, and we do need to bring the level down."