Cuban President Raul Castro sent a congratulatory message to North Korean leader Kim Jong-un for his recent appointment to the chairmanship of the ruling Workers' Party of Korea, the communist country's official news outlet said Thursday.

Kim was elected chairman of the North's ruling party in the recent four-day party congress which closed on Monday. The move is expected to further consolidate his hereditary one-man leadership over the reclusive country.

Calling Kim "honorable comrade," Castro said "From the bottom of my heart, I extend my congratulations to you for being elected the chairman of the party in the 7th congress of the WPK," in the message dated Monday, according to the (Korean) Central TV Broadcasting Station, monitored in Seoul.

Castro, who is the First Secretary of Cuba's Communist Party, expressed his hope that their countries' parties would further intensify their friendship and collaboration in their pursuit of socialist national building.

The North Korean leader sent his own message to Castro last month when the Cuban party held its congress, calling for closer bilateral relations. (Yonhap)