Kim Jong-un
North Korean leader Kim Jong-un writes condolence letter to Cuban President Raul Castro over the death of Fidel Castro KCNA via Reuters

North Korea has declared three days of mourning beginning on Monday, 28 November to mark the death of Cuban leader Fidel Castro. Hailing the Cuban revolutionary as a "comrade and close friend" of North Korean people, the North Korean leader Kim Jong-un has also penned a condolence letter to President Raul Castro.

The ruling party's central seat of power - the presidium of the Supreme People's Assembly and the cabinet had jointly decided that there will be a three-day mourning period - Pyongyang's state-run mouthpieces say. According to the regime-backed Rodong Sinmun, the North Korea's top political bodies have decided to "hoist flags at half-mast at major organisations and designated places".

The death of Castro, who came to power in 1959 ushering in a communist revolution, was announced on Friday, 25 November. Cuba had declared nine days of mourning to commemorate the 90-year-old.

In his letter, Kim wrote: "He was the close friend and comrade of the Korean people who made all efforts to strengthen the friendly and cooperative relations between the two parties, governments and peoples of our two countries and extended firm support and encouragement to our efforts for national reunification and just cause with the invariable revolutionary principle and obligation for over half a century."

"Though he passed away, the precious feats he performed will remain forever in the hearts of the peoples of our two countries and the hearts of progressive mankind," he wrote.

North Korea and Cuba maintained close ties throughout the Cold War era. Havana has remained one of Pyongyang's strongest international allies for over half of the century – despite an increasing economic cooperation with North Korea's rival, Seoul.