South Korea, a close US ally, was under growing pressure to expand its roles in Proliferation Security Initiative (PSI) drills, following the communist country's October 9 nuclear test.

North Korea November 1 confirmed it would return to six-party talks aimed at ending its nuclear weapons programmes, on condition the issue of lifting US financial sanctions imposed against it was settled during the negotiations.

"We have reached a conclusion that we support the spirit of PSI, but we should confine ourselves to our current roles in the drills," Kim Won-Wung told AFP.

"Now that Pyongyang has decided to return to six-party talks, we don't have to take a step that wouldn't be helpful for creating an atmosphere for dialogue," he said.

The North denounced South Korea for sending a government delegation of three observers to PSI drills off Bahrain late last month, arguing the drills "constitute part of the sanctions, blockade and military pressure".

The South has sent observers to the sea drills instead of sending ships or troops to join the maneuvers.

Officials in Seoul said South Korea's active participation in the PSI exercises could lead to armed clashes with North Korea, with which the South has been technically at war since a bloody 1950-1953 conflict.

The two Koreas had several sailors killed and ships sunk in clashes in disputed waters in 1999 and 2002.

The UN Security Council has adopted a resolution to broaden sanctions, including cargo inspections, against North Korea for its nuclear test.

North Korea has since told South Korea not to enforce the sanctions, which Pyongyang said were tantamount to a declaration of war.

Previous drills involved high-speed maritime chases and commandos rappelling onto vessels from helicopters or clambering aboard from fast boats, with inspectors in chemical suits searching suspect cargo.

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