SEOUL, Jan 17 (Reuters) - The two Koreas will field a combined womens ice hockey team and march together under one flag at next months Winter Olympics in the South, Seoul said on Wednesday, after a new round of talks amid a thaw in cross-border ties.

North and South Korea have been talking since last week - for the first time in more than two years - about the Olympics, offering a respite from a months-long standoff over Pyongyangs nuclear and missile programs, although Japan urged caution over the Norths charm offensive.

The two Koreas will compete as a unified team in the Olympics for the first time, though they have joined forces at other international sports events before.

North Korea will send a delegation of more than 400, including 230 cheerleaders, 140 artists and 30 Taekwondo players for a demonstration, a joint press statement released by Seouls Unification Ministry said, adding the precise number of athletes will be hammered out after discussions with the IOC scheduled for later this week.

Prior to the Games, the sides will carry out joint training for skiers at the Norths Masik Pass resort and a cultural event at the Mount Kumgang resort, for which Seoul officials plan to visit the sites next week.

Under the circumstances where inter-Korean (relations) are extremely strained, in fact just some 20 days ago we werent expecting North Korea would participate in the Olympics, said Chun Hae-sung, the Souths chief negotiator and vice unification minister.

It would have a significant meaning if the South and North show reconciliation and unity, for example through a joint march.

The North Korean delegation will begin arriving in South Korea on Jan. 25, according to the joint statement.

The North will separately send a 150-strong delegation to the Paralympics, Chun said.