On his upcoming tour of Asia, U.S. President Barack Obama is expected to stay in South Korea less than two days, while considering a three-day state visit to Japan, diplomatic sources here said Wednesday.

The White House earlier announced that Obama will travel to Japan, South Korea, Malaysia and the Philippines in late April. It stopped short of revealing detailed schedules.

"Consultations on President Obama's itinerary are in the final stage. He is expected to make an overnight stay in Seoul," an informed source said. It would be his fourth trip to Seoul since taking office in 2009.

Obama will likely accept Japan's request for a state visit to include two nights, added the source.

His trip to Washington's key regional allies would provide a chance to show strong trilateral cooperation at a time when tensions run high on the Korean Peninsula and concerns are growing over China's rapid military build-up, according to the source.

Obama hosted a landmark three-way meeting with South Korean President Park Geun-hye and Japan's Prime Minister Shinzo Abe in the Netherlands last month on the sidelines of the Nuclear Security Summit.

They agreed to hold tripartite talks among the top nuclear envoys of the three countries in the near future.

Another source said the talks will be held in Washington next week, although an exact date has yet to be set.

It would the first gathering of the top nuclear envoys of the three countries since November.

South Korea's presidential office, Cheong Wa Dae, has yet to fill the post that has been vacant since Cho Tae-yong was promoted to the position of vice foreign minister in late February.

"Cheong Wa Dae is expected to name Cho's successor this week,"

the source said.

Two main candidates are Chang Ho-jin, special adviser to South Korea's foreign minister, and Hwang Joon-kook, who led Seoul's recent negotiations with Washington on sharing the financial burden of stationing American troops on the peninsula. (Yonhap)