This image, captured from the website of Cuba's presidential office, Sept. 19, shows Cuban Vice President Salvador Valdes Mesa, center, with North Korea's new ambassador to Cuba, Han Su-chol, right. Yonhap

North Korea's new ambassador to Cuba has vowed to further strengthen ties with Havana, seven months after South Korea established diplomatic ties with Cuba in a significant diplomatic setback for Pyongyang.

Han Su-chol presented his credentials, according to Cuba's presidential office Thursday (local time), more than six months after his predecessor returned home.

Cuban Vice President Salvador Valdes Mesa accepted the credentials.

Han expressed his commitment to "actively strengthen and expand cooperation in all spheres," emphasizing the historic ties that have united the two countries for years, the office said.

In response, the Cuban vice president referred to North Korea as a "sister nation" and stated that the two countries are united by a long history of struggle against imperialism and a common enemy, according to the presidential office.

In February, South Korea and Cuba established formal diplomatic ties in a surprising move that many viewed as a diplomatic blow to North Korea, which has long maintained close relations with the Caribbean nation.

The following month, North Korea's then ambassador to Cuba, Ma Chol-su, left the country, an event some observers interpreted as a display of North Korea's discontent over the new diplomatic relationship between South Korea and Cuba.

Ri Il-gyu, a former counselor of political affairs at the North Korean Embassy in Cuba, recently told Yonhap News Agency that North Korea would "never abandon" its ties with Cuba.

Ri also revealed that members of North Korea's diplomatic mission in Cuba were summoned back to the country after his defection to South Korea with his family last November. (Yonhap)