Seoul  - North Korea charged Thursday that a naval skirmish this week with South Korea was a conspiracy by its neighbour aimed at thwarting a current thaw in tensions.

Navy vessels from the two Koreas exchanged fire Tuesday, the first such incident in seven years. According to South Korea's military, a northern vessel crossed the disputed sea border in the Yellow Sea and opened fire after a southern ship fired warning shots.

Pyongyang, however, blamed South Korea for the clash, accusing it of having violated the Northern Limit Line off their west coasts.

"This armed clash in the Yellow Sea was not some simple, accidental incident but a deliberate, planned provocation by the South Korean military that contrives to escalate tension on the Korean Peninsula," said the Rodong Sinmun newspaper, a government mouthpiece.

The paper accused South Korea's military and conservative forces of plotting the clash to torpedo current "positive signs" for dialogue.

While there were no South Korean casualties from Tuesday's clash, the northern boat had been several damaged, the South's Yonhap News Agency reported. North Korea reportedly suffered one death and three of its sailors were wounded, the agency said, citing a South Korean defence official.

The incident occurred days before US President Barack Obama's visit to Asia. Obama was scheduled to meet with his South Korean counterpart, Lee Myung Bak, on November 19.

Pyongyang's nuclear weapons programme was expected to feature prominently in the talks.

On Wednesday, US Secretary of State Hillary Rodham Clinton said the naval clash would not affect Washington's decision to send a special envoy to the Stalinist state.

Ambassador Stephen Bosworth would visit Pyongyang "in the near future" to persuade North Korea to return to international talks on ending its nuclear weapons programme, Clinton said on the sidelines of the summit of the Asia-Pacific Economic Cooperation (APEC) forum. (dpa)