Afghan officials say a suicide bomber has attacked a mosque in the southern city of Kandahar, killing four people during a memorial service for the assassinated half-brother of President Hamid Karzai.

The Interior Ministry said the attack Thursday killed the head of the provincial religious council and three others. Local officials said another 13 people were wounded.

No one immediately claimed responsibility for the blast.

The attack comes a day after Mr. Karzai led thousands of mourners at the funeral of Ahmad Wali Karzai, who was chief of the Kandahar provincial council and a powerful figure in the country's south

He was shot dead on Tuesday at his home in Kandahar city by a trusted longtime member of his own security team. The man, identified as Sardar Mohammad, was then killed by other guards.

The Taliban claimed responsibility for the assassination. But Afghan officials said it is not clear whether Wali Karzai's killing was related to the insurgency or to an internal feud.

Kandahar is the birthplace of the Taliban and violence has increased as international troops work to clear the south of insurgents.

On Wednesday, the governor of nearby Helmand province escaped injury after his convoy was hit by a roadside bomb while traveling to the funeral. Two security officials accompanying Governor Gulab Mangal were wounded in the attack.

Ahmad Wali Karzai was considered the most influential official in southern Afghanistan. Analysts say his death creates a power vacuum in the volatile region, where President Karzai relied on his brother to help maintain support among his ethnic Pashtun community.

While Wali Karzai was seen as a key power broker and an ally of the international forces fighting the Taliban, he was also accused of corruption, drug trafficking, and being on the CIA's payroll — allegations he denied.