Vancouver meeting focuses on sanctions as Koreas explore detente

* Officials from 20 nations gather in Vancouver for Korea talks

* Talks to focus on better implementation of N.Korea sanctions

* Maritime security, interdicting ships to be discussed

* China, N.Korea's main ally, and Russia not attending talks

* Beijing sees meeting as example of 'Cold War' thinking (Adds Chinese envoy comments, paragraph 12)

By David Ljunggren and David Brunnstrom

VANCOUVER, Jan 15 (Reuters) - A meeting of states that backed South Korea in the Korean war will look at ways to better implement sanctions to push North Korea to abandon its nuclear weapons, officials said, even as the North and South explore detente ahead of next month's Winter Olympics.

Foreign ministers and senior officials from 20 nations will hold a full-day meeting in Vancouver on Tuesday, hosted by the United States and Canada, looking to increase diplomatic and financial pressure on North Korea to give up development of nuclear missiles capable of hitting the United States, a program that has raised fears of a new war.

Canadian and U.S. officials say the meeting will discuss ways to ensure implementation of wide-ranging U.N. sanctions, including steps agreed last month to further limit Pyongyang's access to refined petroleum products, crude oil and industrial goods.

Brian Hook, the U.S. State Department's director of policy planning, said last week that participants, including U.S. Secretary of State Rex Tillerson, would probe how to boost maritime security around North Korea and options to interdict ships carrying prohibited goods in violation of sanctions.

The Vancouver meeting primarily groups nations that assisted South Korea in the 1950-53 Korean War, as well as South Korea and Japan. China and Russia, which backed the North in the war but have since agreed to U.N. sanctions on Pyongyang, will not be attending.

South Korea and the United States are technically still at war with the North because the 1950-53 Korean War ended with a truce, not a peace treaty.

TENSIONS EASING?

The meeting was announced after North Korea tested its biggest ever intercontinental ballistic missile in late November, but now comes amid signs that tensions on the Korean peninsula are easing, at least temporarily.

North and South Korea held formal talks this month for the first time in two years and Pyongyang said it would send athletes across the border to the Pyeongchang Winter Olympics to be held in South Korea next month.

China, North Korea's main ally and principal trading partner, has backed successive rounds of U.N. sanctions, but has also urged dialogue to solve the crisis. It has reacted angrily to the Vancouver meeting as an example of "Cold War" thinking.