BEIJING, Dec 19, 2011 (AFP) - China on Monday offered its "deep condolences" on the death of the North Korean leader Kim Jong Il, a foreign ministry spokesman said.

"We are shocked to learn that DPRK top leader comrade Kim Jong Il passed away and we hereby express our deep condolences on his demise and send sincere regards to the DPRK people," foreign ministry spokesman Liu Weimin said.

China is a neighbour and close ally of the isolated Stalinist state, whose official media announced on Monday that its leader had died of a heart attack at the age of 69 and that his son, Kim Jong-Un, would succeed him.

Analysts said his death would be a source of concern to stability-obsessed leaders in Beijing who would be anxious that Kim Jong-Un has not had enough time to secure control over the country's government and military.

More than 21,700 North Koreans have fled their impoverished and hunger-stricken homeland since the 1950-1953 Korean War, the vast majority in recent years.

They typically escape on foot to China before travelling to a third country. Beijing is worried that if the North Korea regime were to collapse the country could be inundated with refugees.