According to media reports, 74-year-old Mumtaz also denounced Asif Ali Zardari, Benazir’s widower and the new co-chairman of the Pakistan People’s Party (PPP), as an opportunist and said that he doubted the authenticity of the will that Bilwal, the 19-year-old son of the former leader, read out at the family home on Sunday.

The PPP said that the ‘will’ nominated Zardari as Benazir’s successor, but he immediately stepped down in his son’s favour, on the understanding that the father would run the party until the son had completed his studies at Oxford in three years. Bilawal, who flew to Dubai early on Tuesday, changed his name on Sunday from Bilawal Zardari to Bilawal Bhutto Zardari in a symbolic move asserting his right to lead the Bhutto dynasty. “It’s very suspect”, he said. “Suddenly a will has come into existence that nobody has seen before.” Mumtaz - first cousin of Zulfiqar Ali Bhutto, Benazir’s father - said that the name change violated tribal norms and that Bilawal had no right to lead the party as he was not a Bhutto.

Mumtaz, leader of the 700,000-strong Bhutto tribe, said the leadership should have passed to Sanam Bhutto, Benazir’s younger sister, who is based in London, or to one of the two children of Ghinwa Bhutto, the widow of Murtaza, Benazir’s brother. Murtaza was killed in a police shootout in Karachi in 1996, when Benazir was prime minister. Ghinwa, who blames Benazir for her husband’s death, lives in Karachi with Zulfiqar Ali Bhutto Jr, her 18-year-old son and Fatima Bhutto, her 25-year-old daughter and newspaper columnist who was one of Benazir’s harshest critics. The report quoted Farhatullah Babar, a PPP spokesman, saying that Sanam had endorsed Bilawal’s leadership added “Whatever Mumtaz is saying he is saying out of frustration and not out of love.”