The government is stepping up diplomatic efforts to stop North Korea from conducting a nuclear test.

The North is expected to carry out a test between Sunday and Tuesday.

Officials in Seoul are having a series of phone conversations with other parties to the six-way talks, trying to draw up measures to deal with the volatile situation.

Chief nuclear negotiator Chun Yung-woo will fly to Beijing to discuss bilateral measures to prevent the nuclear test.

Seoul says it will also cooperate closely with member countries of the U.N. Security Council to urge North Korea to scrap its nuclear test plan and return to the six-party talks.

In addition, South Korea is known to be sending a message against a nuclear test to the North via diplomatic channels in the United States, China and Russia.

But Seoul says foreign reports of an imminent nuclear test are not based on hard evidence, ruling out signs of a test anytime soon.