The two locked horns over nuclear non-proliferation in the second of three election debates at Washington University here, ahead of the November 2 election.

Bush said the Democrat's call for a direct dialogue with Pyongyang would jeopardize six-party talks he had launched bringing in the Asian powers.

"It is naive and dangerous to take a policy that he suggested the other day, which is to have bilateral relations with North Korea," said the Republican president.

"He's the person accusing me of not acting multilaterally," Bush said. "He now wants to take the six-party talks we have ... undermine them by having by bilateral talks."

Bush said his predecessor, Bill Clinton, had pressed bilateral talks with the North Koreans and they ended up not honoring an agreement to suspend their activities in return for fuel and help in building light-water reactors.

"Of course we're paying attention to these," Bush said. "That's why, in my speech to the Congress, I said there's an axis of evil, Iraq, Iran and North Korea, and we're paying attention to it, and we're making progress."

Kerry countered that while the administration was dealing with Iraq, Iran was moving towards production of enriched uranium and "North Korea has moved from one bomb, maybe, to four to seven bombs."

"For two years, the president didn't even engage with North Korea, did nothing at all, while it was growing more dangerous. ... We were safer before President Bush came to office."

The Democrat said Bush "took his eye off the ball" with the invasion of Iraq, diverting attention from Osama bin Laden and the nuclear non-proliferation campaign. "Iran is now more dangerous and so is North Korea with nuclear weapons."

"I'm going to lead the world in the greatest counter-proliferation effort and if we have to get tough with Iran, believe me, we will get tough," Kerry said.

He also criticized the president's move to develop a bunker-busting nuclear weapon. "It's very hard to get other countries to give up their weapons when you're busy developing a new one."

Bush, making a joking reference to his facial grimaces that were widely considered to have cost him points in the first debate last week, said Kerry's answer "almost made me want to scowl."

"He keeps talking about let the (weapons) inspectors do their job. It's naive and dangerous to say that," said Bush, adding that the latest report on Iraq showed Saddam had been deceiving UN weapons inspectors in Iraq.

Bush said his administration was making progress on nuclear non-proliferation and said of Iran, "I fully understand the threat.

"And that's why we're doing what he (Kerry) suggested we do. Get the Brits, the Germans and the French to go make it very clear to the Iranians" they must give up their nuclear weapons program.

Clinton's former secretary of state Madeleine Albright, who sat down with North Korean leader Kim Jong-Il in 2000, said nothing would be achieved with Pyongyang until top US officials got personally involved.

"As one who has had the dubious pleasure or honor of talking to Kim Jong-Il, I think it is essential to have face-to-face talks to deliver a tough message to him," Albright said after the debate.

She accused Bush of "subcontracting out" US foreign policy to China over North Korea, and said that bilateral US-North Korean talks could take place under the umbrella of the six-party talks.