HANOI, July 22, 2010 (AFP) - US Secretary of State Hillary Clinton arrived in Vietnam on Thursday for Asia-Pacific security talks involving China and North Korea amid tensions over the sinking of a South Korean warship.

State Department officials said Clinton would ask Beijing to increase the pressure on its communist ally North Korea during bilateral talks with Chinese Foreign Minister Yang Jiechi in Hanoi later Thursday.

Clinton announced new sanctions against the North during a trip to South Korea on Wednesday, when she also visited the demilitarised zone with Defense Secretary Robert Gates.

The United States is also planning massive naval drills with the South beginning Sunday in a move that has angered the North and prompted Beijing to warn against any measures that might "aggravate" the situation.

Clinton said Wednesday the sanctions were "directed at the destabilising, illicit and provocative policies" of the North Korean government but were not aimed at the isolated country's people.

Ri Tong Il, a spokesman for the North Korean delegation at the regional security talks starting Friday, said the measures were "in violation" of a July 9 UN statement on the sinking of the warship in the Yellow Sea.

South Korea, the United States and other nations - citing the findings of a multinational investigation - have accused the North of sending a submarine to torpedo the ship with the loss of 46 lives.

Pyongyang angrily denies the allegations and China has not blamed its communist ally.

The UN condemned the attack as a threat to regional peace, expressed deep concern at the findings of the investigation but noted the North's denial and did not apportion blame - a result hailed as a "victory" in Pyongyang.

Ri added that the imminent naval exercises in the Sea of Japan - relocated from the Yellow Sea due to Chinese objections - were another "violation" of the Security Council statement.

Clinton will take part in the 27-member ASEAN Regional Forum (ARF) security dialogue on Friday, alongside the foreign ministers of the five other parties involved in nuclear disarmament talks with Pyongyang - China, Japan, Russia and North and South Korea.

State Department spokesman Philip Crowley said Clinton would ask Chinese Foreign Minister Yang to look at additional steps to pressure nuclear-armed North Korea.

"We will be consulting with China (on) what we think (are) additional steps that it can take," he told reporters in Washington on Wednesday.

"The secretary will have a chance to explain to Foreign Minister Yang what we have in mind here and the way forward not only on issues related to North Korea but also issues related to Iran."

Crowley praised China's response to North Korea, saying that it has "aggressively implemented" last year's Security Council resolutions that tightened sanctions aimed at Pyongyang's military programme.

But a number of US lawmakers and pundits have accused China of going easy on North Korea as it finds the status quo to be in its best interest. Pyongyang counts on China as its primary political and economic supporter.

Crowley said that Robert Einhorn, the US envoy on non-proliferation, would travel in early August to encourage enhancing enforcement of North Korea sanctions.

"We would like to see other countries also take the same kinds of national steps that we've announced," Crowley said.

"We hope (greater sanctions) have an impact on the core leadership which will, I think, change their calculations about how they engage with the United States and other countries," he said.