WASHINGTON - U.S. Secretary of State Hillary Clinton said on Sunday that major powers wanted North Korea to return to negotiations over its nuclear program but would not reward any provocative actions.

We are not going to reward them for half-measures. They now know what we in the world community expect, said Clinton in an interview with NBC's Meet the Press program.

We still want North Korea to come back to the negotiating table, to be part of an international effort that will lead to denuclearization she added.

Clinton pointed to great cooperation from countries dealing with North Korea -- Japan, China, South Korea and Russia -- and said they were all vigorously implementing U.N. sanctions strengthened after North Korea's May 25 nuclear test and several missile launches.

She highlighted the role of China, which is sending a string of senior officials to Washington this week for talks on economic and strategic links with the United States. North Korea is expected to be raised in those discussions.

On North Korea we have been extremely gratified by their (China's) forward-leaning commitment to sanctions and the private messages they have conveyed to the North Koreans.

Clinton and North Korea have sparred verbally in recent days, with her accusing Pyongyang of behaving like an unruly child. The North retorted that the top U.S. diplomat was vulgar and by no means intelligent.

Clinton said the North was very isolated and this had been proven at a meeting of South Asian nations in Thailand last week when participants ignored Pyongyang's representative because of what she called provocative behavior.

I was struck by the body language. They don't have any friends left, she said of North Korea, in new comments likely to ratchet up tensions between the two.

Two U.S. journalists have been held by North Korea since March and Clinton reiterated an appeal for their release, saying their case should be seen separately from tensions between Washington and the North over its nuclear ambitions.

We are pursuing every lead we have, she said of the two women, adding that they were apparently being treated well.

Laura Ling and Euna Lee of the U.S. media group Current TV were arrested in March near the China-North Korea border, convicted of great crimes and sentenced to 12 years hard labor.

(Additional reporting by Alister Bull, editing by Anthony Boadle)