Kim Jong-un, the North Korean dictator, reportedly ordered the execution of his uncle and mentor in December 2013 after learning that Jang Song-thaek had proposed to China that it support a coup to replace Mr Kim with his half-brother, Kim Jong-nam.

Mr Jang met in Beijing with Hu Jintao, the then-Chinese president, in August 2012, according to reports in Japan's Nikkei Asian Review. Mr Jang had cultivated close business and political ties with China and was trusted by Beijing.

Sources told the newspaper that Mr Jang proposed a plot to overthrow Mr Kim, with Beijing's assistance, and to replace him with his oldest half-brother.

Mr Hu was not in a position to give an immediate answer to the suggestion, however, as he was facing an internal crisis of his own. Mr Hu's closest adviser, Ling Jihua, was facing disgrace after his fast-living son was killed in a speeding Ferrari when it crashed in Beijing.