Amid speculations of being 'gravely ill' following a heart surgery, North Korean supreme leader Kim Jong-un has reportedly sent a diplomatic letter to Syrian President Bashar as-Assad.

Daily NK, an online newspaper based in South Korea that focuses on North Korea, reported that Kim received a cardiovascular system procedure on April 12. According to the news site, Kim received the treatment because of "excessive smoking, obesity, and overwork, and is now receiving treatment in a villa in Hyangsan County following his procedure.

On Tuesday, CNN, citing an unnamed U.S. official with direct knowledge, reported that Washington is "monitoring intelligence" that Kim is in "grave danger after a surgery."

Kim Jong-un pens Thank You note from an undisclosed location

Laying the rumours of being 'gravely ill or dead' to rest, the North Korean leader expressed his gratitude to the Syrian President in return of latter's congratulatory message on the anniversary of Kim's late grandfather birthday birth last week.

Kim Jong-un
Kim Jong-un Pixabay

Quoting Korean Central News Agency (KCNA), Yonhap News Agency said: "Kim Jong Un, in his message, expressed his deep thanks to the president of the Syrian Arab Republic for sending his heartfelt message of greeting, reflecting the warm respect for President Kim Il Sung, who is always alive in the hearts of the Korean people and the world progressives, on the occasion of his 108th birth anniversary."

"Expressing the belief that the DPRK-Syria friendly and cooperative ties would grow stronger true to the noble intention of the preceding leaders and the desire of the peoples of the two countries, the message wished the Syrian president good health and greater success in his responsible work," added the state media.

Kim Jong-un sends birthday wishes to Cuban President

Earlier, The Pyongyang Times reported that Kim had sent a congratulatory note to the Cuban President Miguel Mario Diaz-Canel Bermudez on his 60th birthday.

The publication reported that Kim lauded the Cubans for bringing great successes in their efforts to firmly protect the gains of socialism and make socio-economic development, smashing the frantic sanctions and blockade of the hostile forces, under the leadership of the president, expressing invariable support to and solidarity with the cause of justice of the Cuban party, government and people.

"Expressing the belief that the traditional relations of friendship and cooperation between the two parties and peoples of two countries forged through the struggle for realizing the cause of socialism would steadily be carried forward and developed in line with the requirements of the new era by their common will and efforts, he sincerely wished the Cuban president and all his family members good health and happiness and greater successes in his responsible work," reported the paper.