KABUL, Afghanistan - Several hundred Afghan and international dignitaries went to the presidential palace on Friday to express their sympathies to Afghan President Hamid Karzai, whose half brother was assassinated earlier this week at his home in southern Afghanistan.

They joined Karzai for prayers in a mosque at the palace, sitting cross-legged on rugs to remember Ahmed Wali Karzai, a powerful and controversial man in Kandahar province and throughout the south. Tuesday's slaying of Wali Karzai left the president without a powerful partner and threatened to create a power vacuum in the spiritual birthplace of the Taliban.

U.S. Gen. David Petraeus, the top commander of U.S. and NATO forces in Afghanistan, U.S. Ambassador Karl Eikenberry and UN envoy Staffan de Mistura attended the memorial along with Afghan ministers, lawmakers and military leaders. Karzai sat by the door of the mosque next to his bodyguard and Afghan Vice President Mohammed Karim Khalili and spoke with the visiting dignitaries as they filed by.

Wali Karzai, who was assassinated by a close associate, was head of the Kandahar provincial council, the influential Popalzai tribe and the Afghan president's confidant and emissary.

Beyond his more official roles, Wali Karzai was also known as a master operator who played Kandahar's hard-line tribal and political factions against one another to retain ultimate control over the restive province. Even the international alliance begrudgingly accepted Wali Karzai's sweeping influence in southern Afghanistan, despite their strong suspicions that he was involved in opium trafficking, smuggling and other criminal enterprises.

His death has raised fear that security will deteriorate in the already volatile south.

On Thursday, a man hiding explosives in his turban blew himself up in Kandahar inside a mosque where other Afghan officials were attending a memorial service for the president's brother. Five people were killed, including a child and Hekmatullah Hekmat, the head of the provincial clerical council. Fifteen others were wounded in the blast.

Separately, violence in southern Afghanistan claimed the lives of nine civilians.

Their deaths in Helmand province were reported Friday, a day after the UN announced that the number of Afghan civilians killed in war-related violence rose 15 per cent in the first half of the year. The UN says 1,462 civilians died in the first six months of the year -- up from 1,271 in the same period last year.

Afghan officials said five civilians, including two children, were killed Friday when their vehicle hit a roadside bomb in Sangin district.

Four others died Thursday night. Two were killed in Nawa district when their car hit a roadside bomb. And in Gereshk district, insurgents targeting Afghan policemen mistakenly shot two civilians leaving a wedding on a motorbike, officials said.