A suicide attacker killed a cousin of outgoing Afghan President Hamid Karzai near the volatile southern city of Kandahar on Tuesday, officials said, raising tensions during a struggle over the contested election result.

Hashmat Karzai was a campaign manager in Kandahar for Ashraf Ghani, one of the two presidential candidates involved in a bitter dispute over fraud that threatens to pitch the country into worsening instability.

Hashmat Karzai, who famously owned a pet lion, was killed by a man with explosives hidden inside his turban when visitors arrived to celebrate Eid, the holiday marking the end of the Muslim holy month of Ramzan.

"A suicide bomber disguised as a guest came to Hashmat Karzai's house to greet him," Dawa Khan Minapal, the Kandahar provincial governor's spokesman, told AFP.

"After he hugged Hashmat, he blew up his explosives and killed him."

Ghani and opposition leader Abdullah Abdullah are at loggerheads over the June 14 second-round election, which has been mired in allegations of massive fraud.