Republican Curt Weldon said his Congressional delegation held "overwhelmingly positive" talks with senior North Korean officials including number two leader Kim Yong-Nam and Foreign Minister Paek Nam-Sun, but parties to the multilateral talks must do more to push forward the process.

As Weldon's delegation wrapped up its visit, North Korea said Friday it would resume talks on its nuclear weapons drive if US President George W. Bush toned down his rhetoric and formulated a more friendly policy towards Pyongyang.

"I'm optimistic but I'm also concerned, we don't want to throw up this opportunity," Weldon told a press conference.

"We can't do the negotiations, that's not our job, our job is to help jump-start the process. Now it's up to the governments of the six countries to do their jobs," he said.

He repeated his statement in Seoul Friday that he expected the next round of six-party talks to be scheduled "within weeks."

But he added the United States had to be careful not to jeopardise the current good atmosphere.

North Korea will watch out to see "whether or not there is going to be any inflammatory rhetoric coming out over the next several weeks" in the run-up to Bush's inauguration for a second term, Weldon said.

Bush used his 2002 State of the Union speech to brand North Korea part of an "axis of evil," a term that enraged Pyongyang's leadership.

Republican lawmaker Roscoe Bartlett said it must not be left to North Korea to make all the effort.

"If the two parties are 20 steps (apart), North Korea is not going to take 19 and a half steps first," he said. "Neither side should expect the other side to make too big a step the first time."

Weldon said Pyongyang had invited his delegation back for another trip.

Weldon said China responded positively to the delegation's visit and said foreign ministry officials had commended their efforts as creating "a window of historical opportunities" amid the stalled negotiations.

Weldon said an upbeat response was also evident from the conciliatory statement issued by North Korea's official Korean Central News Agencyat the end of the four-day visit of the six-member US congressional delegation.

"The DPRK (North Korea) would not stand against the US but respect and treat it as a friend unless the latter slanders the former's system and interferes in its internal affairs," KCNA said Friday.

After attending three rounds of inconclusive talks, North Korea boycotted a fourth round scheduled for last September in Beijing.

Washington has demanded North Korea scrap its nuclear weapons drive without preconditions. Pyongyang is holding out for rewards before eliminating its atomic programmes.

North Korea has declared it will wait and see how Bush's second-term administration shapes its North Korea policy before deciding whether to return to the nuclear forum.

The standoff between North Korea and the United States erupted in October 2002 over Pyongyang's nuclear weapons ambitions.

Three rounds of multilateral talks, involving the two Koreas, China, Japan, Russia and the United States, have since then taken place but produced few tangible results.