U.S. President George W. Bush has warned North Korea against nuclear proliferation if it wants progress in the six-way nuclear talks.

Bush told reporters Thursday that the U.S. expects Pyongyang to stop any proliferation activities and to honor its commitment to give up nuclear weapons and weapons programs.

However, Bush declined to answer questions about U.S. media reports that North Korea may have provided Syria with nuclear material.

Earlier on Tuesday, Pyongyang and Damascus denied all charges of nuclear collaboration, with the Syrians accusing U.S. officials of spreading such allegations to protect Israel.

Israeli forces conducted an aerial raid on Syria early this month targeting sites that some Israeli and U.S. officials say could be linked to a covert nuclear program.