Assistant Secretary of State Christopher Hill faced tough questioning by lawmakers at a committee hearing on the six-nation talks, in which North Korea has promised to abandon its nuclear program.

The legislators questioned the US administration's diplomatic approach with North Korea citing reports that Pyongyang may have assisted Syria to start building a nuclear reactor. Israel reportedly launched an air strike against the suspected site in September.

Hill said he could not discuss North Korea's alleged role in Syria's nuclear program at an open congressional hearing because that information was "classified."

"I'm not in a position here to discuss intelligence matters, which is the level one would need to discuss questions whether they did or did not," Hill said.

Asked by Democratric Representative David Scott of Georgia if the issue had been brought up in disarmament talks with North Korea, Hill said: "Yes, I have raised this issue."

The US diplomat said the disarmament deal would not go ahead if North Korea was found to be smuggling nuclear arms, equipment or know-how abroad.

"I think throughout the process we have made it clear we cannot accept any agreement that has us winking at proliferation issues. So proliferation, or non-proliferation, has to be at the heart of any agreement," Hill said.

Republican Ted Poe charged the White House had failed to brief lawmakers on intelligence related to North Korea's activities in Syria.

"I'm concerned about what they're doing in Syria. And I would like you to tell me why you can't tell us what they're doing in Syria?" said Poe.

Under the six-nation talks, North Korea has agreed to dismantle its nuclear weapons programs in return for a broad package of economic and diplomatic incentives.

Hill's testimony at the House Subcommittee on Terrorism, Non-Proliferation and Trade came as President George W. Bush faced criticism from fellow Republicans and a former administration official over the deal with North Korea.

In a commentary published this week in the Wall Street Journal, two Republican members of Congress said the reports of North Korean involvement raised serious concerns about the disarmament talks.

They complained that "only a handful" of lawmakers were given intelligence briefings by the Bush administration on the Israeli air strike.

Former US ambassador to the UN John Bolton, breaking ranks with the administration, has criticized the six-party talks with North Korea and reportedly lobbied Republican lawmakers on the issue.

North Korea has angrily denied sharing atomic know-how with Damascus.

If confirmed, the reports of nuclear cooperation between North Korea and Syria would deal a blow to Bush who has portrayed US policy towards Pyongyang as a a success story.

All rights reserved. © 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.