Senior US diplomats will visit Russia and South Korea next week to discuss continuing efforts to obtain North Korea's nuclear disarmament, following the death of Pyongyang's leader Kim Jong-Il.

Glyn Davies, special representative for North Korea Policy, will travel to Moscow on Tuesday "to deepen cooperation and share perspectives on North Korea," the State Department said in a statement.

Davies will meet Russian Deputy Foreign Minister Igor Morgulov and Grigoriy Logvinov, the ambassador-at-large for six-party talks, it added.

The six parties involved in suspended negotiations for North Korea's nuclear disarmament are the United States, Russia, China, South Korea, North Korea and Japan.

Davies, whose trip will continue to February 3, will be accompanied by Clifford Hart, the special US envoy for six-party talks.

Meanwhile, Kurt Campbell, the US assistant secretary of state for East Asia and Pacific affairs, will travel to Seoul, South Korea from January 31 until February 1, the State Department said.

In meetings officials from the foreign ministry and presidency, "he will discuss a range of bilateral, regional, and global issues, including recent developments in North Korea," the State Department said.

Campbell met in Washington January 19 with senior officials from Japan and South Korea to coordinate action. In a statement, the countries urged North Korea to recommit to past agreements to end its nuclear program.

Kim's death last month threw into flux US plans for fresh diplomacy with North Korea, including a possible resumption of American food assistance to the impoverished state and more formal talks on ending Pyongyang's nuclear program.

Kim was replaced by a young and untested son, Kim Jong-Un.

Campbell will visit Hanoi, Vietnam from February 1-3 to meet with senior Vietnamese leaders to discuss bilateral and regional issues, the State Department said.

From February 3-4, Campbell will visit Phnom Penh, Cambodia to meet with senior Cambodian government officials to discuss Cambodias role as 2012 ASEAN chair, and ways to further strengthen bilateral ties.

He is due to return to Washington on February 4.