A senior South Korean official is in Washington this week to coordinate the allies' implementation of sanctions on North Korea, a government source said Monday.

Kim Gunn, director-general for North Korean nuclear affairs at the Foreign Ministry, left for Washington late Sunday to meet with State Department and Treasury officials involved in the implementation of sanctions on Pyongyang, the source said on the condition of anonymity.

North Korea has come under a series of tough sanctions for its fourth nuclear test in January and long-range rocket launch in February. Among them are U.N. Security Council sanctions adopted in early March and bilateral sanctions imposed by Washington and Seoul.

Kim's visit comes two weeks after the allies held their first-ever high-level talks on the issue in Seoul.

Kim Hong-kyun, South Korea's special representative for Korean Peninsula peace and security affairs, met with Ambassador Sung Kim, U.S. special representative for North Korea policy, and Daniel Fried, the State Department's coordinator for sanctions policy, to reaffirm their commitments to the faithful implementation of the U.N. sanctions, their respective unilateral sanctions and to strengthening cooperation with China and Russia to increase pressure on Pyongyang.

Last week, South Korea, the U.S. and Japan again stressed their unity in the face of North Korean provocations during a trilateral summit in Washington.

The three countries are also reportedly in talks to hold a vice foreign ministerial meeting in Seoul later this month. (Yonhap)