South Korea yesterday called on the Democratic People's Republic of Korea (DPRK) to unconditionally return to the six-party talks and it also reaffirmed its support for a UN sanctions resolution on DPRK.

"As the government has already clarified, North Korea's nuclear test was a serious threat to the stability and peace on the Korean Peninsula and in Northeast Asia," the South Korean news agency Yonhap quoted a spokesman for the Unification Ministry as saying in a statement.

The spokesman said the Oct. 9 nuclear test was a clear challenge to international efforts to resolve the nuclear dispute peacefully.

"To support and implement the UN Security Council resolution is what the government must do as a member of the United Nations," the spokesman said.

"If the North worries about the future of our nation, it must immediately return to the six-party talks without worsening the situation any further," the spokesman added. The six-party talks involves South Korea, DPRK, Japan, China, Russia and the United States.

Also on Thursday, the Unification Ministry said the South Korean government has decided to prevent the entry of any DPRK personnel suspected of having links to the country's nuclear and other weapons programs.

The measure came as the first visible step South Korea has taken to punish DPRK for its nuclear test.

The DPRK announced on Oct. 9 that it had successfully conducted its first ever nuclear test.

The United Nations Security Council unanimously adopted a resolution on Oct. 14 concerning the nuclear test conducted by the DPRK.

The resolution demands that the DPRK eliminate its nuclear weapons and nuclear programs, and imposes sanctions on the DPRK in spheres related to its nuclear, ballistic missiles and weapons of mass destruction.