BEIJING (REUTERS) - A North Korean envoy told China's president on Friday that his reclusive country was willing to take "positive actions" to ensure peace and stability on the Korean peninsula, as China steps up diplomatic efforts to bring Pyongyang back to talks.

Mr Choe Ryong Hae, a special envoy of North Korean leader Kim Jong Un, met Chinese officials, including President Xi Jinping, in the highest-ranking visit by an official from Pyongyang in about six months.

But Mr Choe made no offer to abandon the North Korea's nuclear programme, limiting the chances of talks with South Korea and the United States, which insists North Korea takes meaningful steps on denuclearisation before there can be dialogue.

Chinese state media said Mr Choe presented a hand-written letter from Mr Kim to Mr Xi at Beijing's Great Hall of the People.

Media provided no details of its contents.

"North Korea is willing to make joint efforts with all parties to appropriately resolve related issues through multilateral dialogue and consultations like the six-party talks, and maintain peace and stability on the peninsula," the official Xinhua news service cited Mr Choe as telling Mr Xi.

"To this end, North Korea is willing to take positive actions," Mr Choe added.

Mr Xi told Mr Choe that the denuclearisation of the peninsula was an aspiration of all peoples and an inevitable trend, saying problems should be resolved through talks.

"China hopes all sides exercise calm and restraint, push for a lessening of tensions, restart the six-party talks process and make unremitting efforts... for long-lasting peace and stability," Mr Xi said.

China has repeatedly urged North Korea to return to the so-called six party talks process, aimed at denuclearisation.

The United States and its allies believe the North violated a 2005 aid-for-denuclearisation deal by conducting a nuclear test in 2006 and pursuing a uranium enrichment programme that would give it a second path to a nuclear weapon in addition to its plutonium-based programme.

The six-party aid-for-disarmament talks, involving the two Koreas, the United States, Japan, Russia and host China, collapsed in 2008 when the North walked away from the deal.

China, North Korea's only real ally, has been pushing for a return to talks after weeks of bellicose words from Pyongyang following new United Nations sanctions after the North's third nuclear test in February.

China has looked on nervously at the ratcheting up of tension, fearful a misstep could plunge the peninsula into war which could envelop northeastern China.

Mr Fan Chonglong, vice-chairman of China's Central Military Commission, expressed that worry in a meeting with Mr Choe.

"In recent years, the state of affairs around the Korean peninsula nuclear issue frequently turns into one escalation of tensions after another," China's Xinhua state news agency quoted mr Fan as saying.

"The conflicting strategies of all parties have intensified, jeopardising peace," Mr Fan said.

China has increasingly expressed its impatience with North Korea, signing up for the new United Nations (UN) sanctions and curtailing Chinese banks' contacts with their North Korean counterparts.

Mr Choe told mr Fan that peace could not be assured although North Korea wanted it in order to build the country, and it was willing to work with all sides in solving problems, Xinhua said.

"The situation on the Korean peninsula and in Northeast Asia is complex and extraordinary, and there is no guarantee of peace," Mr Choe was quoted as saying.

Prof Cai Jian, a North Korean expert at Shanghai's Fudan University, said that while such high-level contact between the two countries was important, especially following the chilling of ties, he did not see a quick resumption of six-party talks.

"The US says if North Korea doesn't clearly renounce its nuclear programme, it won't return to the six-party talks. But if the international community doesn't hold peace talks with North Korea, then North Korea will use that time to develop its nuclear weapons and missiles," Prof Cai said.

Mr Choe and his entourage spent three days in Beijing in full military regalia, in contrast to the mostly civilian leaders he met, though he changed out of his uniform to meet Mr Xi.

"Sending Choe in military uniforms as an envoy to China means North Korea still wants to stick to their right to have a nuclear arsenal," said senior researcher Chang Yong-seok at the Institute for Peace Affairs at Seoul National University.

Mr Choe was dispatched at this time because North Korea is mindful of Mr Xi's talks with US President Barack Obama in early June, analyst Chang said.

Mr Xi is due to hold his first meeting with Mr Obama in the United States and North Korea is expected to be high on the agenda.

South Korean President Park Geun Hye plans to make a state visit to China at the end of June, presidential spokeswoman Kim Haing said on Friday.

"Though China says it can't do everything alone, China still is a country that can exercise considerable influence" over North Korea, Ms Park said during a meeting with US security experts on Thursday.