SEOUL - CHINA'S relations with its traditional ally North Korea have grown cooler since Pyongyang's nuclear test, a top US diplomat was quoted as saying on Thursday.

Visiting US Deputy Secretary of State James Steinberg made the remarks during a meeting with South Korean President Lee Myung-Bak, according to a statement from the Seoul presidential office.

'North Korea is failing to read changes in China's position,' it quoted Mr Steinberg as saying at the private meeting. 'It would be a mistake for the North to believe that it can obtain what it wants through negotiations after staging provocative acts... the United States will never repeat the same mistake,' he reportedly said.

Mr Steinberg is leading a high-level delegation to East Asia to discuss a response to the North's May 25 nuclear test, its second since 2006. Diplomats from the five permanent UN Security Council members plus Japan and South Korea are negotiating in New York about a resolution which could include new financial and other sanctions.

The United States is pushing for tough measures but it is unclear how far China and Russia will go. Moscow's UN envoy Vitaly Churkin said on Wednesday the resolution should not include any 'economic embargoes' against Pyongyang. Mr Lee called for a 'strong, unified response' to the test.

'For the resolution of the North Korean nuclear issue, we need to rebuke the North's wrong behaviour with a UN Security Council resolution and convince the North with one and the same voice to change its course,' he was quoted by his office as saying.

Chinese President Hu Jintao held telephone talks with his US counterpart Barack Obama about North Korea's nuclear programmes, state media in Beijing said on Thursday. They spoke on Wednesday about bilateral relations and exchanged opinions on the current situation on the Korean peninsula, the People's Daily said without giving details.

Mr Steinberg arrived on Tuesday from Japan and will leave on Friday for China, which hosts six-party talks on North Korea's nuclear disarmament. The talks also include the two Koreas, Japan, the US and Russia.

After the UN Security Council censured its April 5 rocket launch, the North announced it was quitting the talks and restarting a programme to make weapons-grade plutonium. Since the atomic test it has launched six short-range missiles, renounced the truce which ended the 1950-1953 Korean War and threatened possible attacks on the South.

South Korean and US troops in the peninsula have gone on heightened alert. Seoul has deployed a high-speed patrol boat armed with ship-to-ship missiles to the disputed border with the North in the Yellow Sea. About 70 of some 90 Chinese fishing boats withdrew overnight from areas near the maritime border, Yonhap news agency said. The area was the scene of bloody naval clashes in 1999 and 2002.

'Their disappearance makes us nervous as that was exactly what happened before the 2002 clash,' Yonhap quoted an unidentified resident of Yeonpyeong Island near the borderline as saying. -- AFP