Resumption of multilateral talks aimed at resolving North Korea's nuclear crisis is increasingly unlikely before the U.S. presidential election in November, South Korean officials and analysts say.

Negotiators from the two Koreas, the United States, China, Russia and Japan are due to meet in Beijing by the end of September for a fourth round of six-way talks to discuss the 21-month-long nuclear standoff.

But prospects have been overshadowed by the recent exchanges of insulting remarks against their top leaders between North Korea and the United States. Pyongyang has already indicated a boycott of the nuclear talks, accusing the United States of using the negotiations to overthrow its communist regime.

South Korea's top nuclear negotiator said on Thursday that he expects no breakthrough in North Korea's nuclear crisis before U.S. presidential elections in November.

Political situations are developing to make it difficult to reach an agreement, said Deputy Foreign Minister Lee Soo-hyuck, who met Chinese officials this week to prepare for another round of six-way talks to resolve the nuclear standoff.

I don't think the situation will allow the United States to reach an agreement one month before the presidential elections, and North Korea is also likely to want to see the outcome of the elections. he said.

Speaking on a local radio program, Lee also said he learned from the six-party talks that it was impossible to develop a proposal that can satisfy both the United States and the North. His comments are the first acknowledgement of stalling nuclear talks by South Korea.

Lee expressed concerns that the hard-won dialogue momentum may be lost if the planned talks fail to open as scheduled. We have to work out a direction at the fourth round of talks so as not to lose the momentum of the dialogue, and based on that we have to prepare for the fifth round of talks, Lee said.

Under the current situation, it is necessary to put together a proposal that is unsatisfactory, but irresistible to North Korea and the United States, he sad.

His skeptical remark came after North Korea railed against U.S. President George W. Bush, calling him a tyrant and an imbecile who is only seeking to overthrow its communist regime.

Earlier this week, the communist country called Bush a fascist tyrant and a human trash and said it can no longer pin any hope on the six-party talks due to Washington's hostile policy against it.

The North's strident rhetoric came in response to remarks by Bush last week in which he called North Korean leader Kim Jong Il a tyrant and urged Kim to give up his nuclear ambitions.

Many analysts in Seoul believe the North has no interest in continuing negotiations with the Bush administration and wants to wait for the result of the U.S. presidential votes in hopes of Democratic opponent John Kerry's winning.

It is uncertain whether the six-party talks will be held in September, considering tensions between the United States and North Korea, said Koh Yu-hwan, a North Korea specialist at Dongguk University.

The North, he says, is seeking to delay negotiations until after November in the hope that the Democratic candidate will win the election and adopt a more flexible approach to the nuclear issue.

The United States has recently stepped up pressure on North Korea, conducting multilateral Proliferation Security Initiative drills, which aim to seize suspected weapons of mass in international waters and airspace.

North Korea blasted the drills as part of a U.S. attempt to isolate and blockade the country. The exercise showed the United States' hostile policy toward North Korea has reached a dangerous phase, it said.

Further increasing tension, the U.S. House of Representatives angered Pyongyang last month when it passed the North Korean Human Rights Act, which is aimed at promoting respect for democracy and protection of fundamental human rights in the Stalinist country. If enacted, it would provide more than $20 million per year for that purpose from 2005 through 2008. The bill is now being considered by the Senate.

North Korea has warned it would never overlook the U.S. act aimed at destroying people-centered socialism of (North) Korean style.

Koh said the prolonged tensions between Pyongyang and Washington would damage inter-Korean ties, which has already been strained. The North has frozen all kinds of cross-border dialogue channels with the South in a protest after the Seoul government secretly organized the airlift of 478 North Korean refugees last month from Vietnam.

South Korea is expected to use this week's visit by a Chinese leader to persuade Beijing to exert stronger influences on North Korea to return to the negotiation table.

Jia Qinglin, who leads the People's Political Consultative Conference as the fourth man in the Chinese hierarchy, arrived in Seoul on Thursday for talks mainly on North Korea's nuclear ambitions.

Jia is scheduled to meet President Roh Moo-hyun, Prime Minister Lee Hai-chan, as well as National Assembly Speaker Kim One-ki before returning home on Monday.