Mumtaz Bhutto, Benazir’s uncle, on Tuesday disputed the appointment of Bilawal, her 19-year-old son, as head of the Pakistan People’s Party (PPP), which she led until her assassination last Thursday.

Mumtaz, 74, also denounced Asif Ali Zardari, the new co-chairman of the PPP, as an opportunist and said that he doubted the authenticity of the will that Bilawal read out at the family home on Sunday. The PPP says 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 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. But Mumtaz — first cousin of Zulfiqar Ali Bhutto— said Bilawal had no right to lead the party as he was not a Bhutto. “You can’t just add a name. You can’t become a Bhutto overnight,” he said, sitting on the terrace of the original Bhutto family home, two miles from the mausoleum where Benazir was buried alongside her father and two brothers on Friday. He said that the PPP leadership should have passed to Sanam Bhutto, Benazir’s younger sister, who is based in London and has no professed interest in politics, or to one of the two children of Ghinwa Bhutto, the widow of Murtaza, Benazir’s brother.

Mumtaz said: “The party came into existence and survived on the name and the sweat and blood of the Bhutto family. Leadership should have gone to Sanam or to Murtaza’s children. The Zardaris have made no sacrifices for the party.”