Around July 4 Clinton will visit the US Pavilion at the Yeosu Expo now underway in the southeastern coastal city, South Korea's Yonhap news agency said, quoting diplomatic sources in Washington.

A South Korean foreign ministry spokesman said he had no information.

She will also hold talks with South Korean officials in Seoul focusing on North Korea's nuclear programme and the situation on the Korean peninsula, Yonhap said.

Clinton's last visit to South Korea was in November last year when she took part in an international aid conference in the southern coastal city of Busan.

Her Asian swing will also take her to Japan and Cambodia, the news agency said.

Clinton said Monday she would visit Tokyo on July 8 to take part in a conference aimed at ensuring social progress in Afghanistan after foreign troops leave.

She will also take part in the Asian Regional Forum in Cambodia, scheduled for July 12-13, Yonhap said, adding the forum could offer the chance of a meeting with North Korea's Foreign Minister Pak Ui-Chun.