KANDAHAR, Afghanistan — Pushing through a ring of his security men, President Hamid Karzai climbed into his slain half-brother's freshly dug grave Wednesday and sobbed alongside the coffin at a funeral attended by thousands of mourners.

Overcome with grief, the president and appealed to his countrymen to stop the violence.

Hours later, a bomb attack killed five French soldiers and an Afghan civilian in the east of the country.

The Taliban claimed responsibility for both attacks. But Afghan officials cast doubt that the militants really were behind the killing of the president's brother. The gunman's motive remained unclear.

Shortly after the funeral, Karzai named another sibling, Shah Wali Karzai, to replace Wali Karzai. The move signaled the importance of continuity in a country where power vacuums are often filled with violent confrontations. Still, the new tribal elder is a relative unknown, and it was unclear if will be as able an operator as Wali Karzai.

"The president will have to be very careful to move quickly to consolidate and maintain his power structure in Kandahar," said Rustam Shah, former Pakistan ambassador to Afghanistan.

Kandahar is the birthplace of the Taliban and site of recent military offensives by the U.S.-led military coalition.

The radical Islamic movement claimed responsibility for the killing, and the president, speaking later at a somber press conference, challenged his insurgent adversaries to give up violence.

"My message for them (the Taliban) is that my countrymen, my brothers, should stop killing their own people," Karzai said. "It is easy to kill and everyone can do it, but the real man is the one who can save people's lives."

In a land of big men, warlords and gangsters, Wali Karzai was all of these. He was the president's bulwark against the Taliban's forces in the south and the enforcer of Karzai's tenuous rule over the Pashtuns who predominate the insurgency.

To the international community, Wali Karzai offered indispensable reach and ruthlessness, but he was also an embarrassment — a partner whose other partners included opium dealers and smugglers.

President Karzai, who flew to Kandahar hours after his brother was shot, led a procession of thousands of mourners under a tight security blanket from the center of Kandahar city to the family's ancestral village of Karz, some 12 miles away.

He was accompanied by his family and some of Afghanistan's most influential leaders, including at least one possible successor to Ahmad Wali Karzai's unofficial crown, Gul Agha Sherzai, currently the governor of eastern Nangarhar province.

Story: After Karzai, who will fill Afghan power void?

The president knelt by the side of his brother's grave clutching his hand, weeping as the crowds looked on. Concerned mourners then pulled the president away, warning him that television cameras were recording his every move.

"I came here to mourn the death of Ahmad Wali Karzai. He was our only hope for everything in Kandahar," cried one mourner, Khan Agha, as attack helicopters circled overhead.

A tearful President Karzai appeared at the fringe of the throng of thousands and pushed toward the lowered coffin.

He paused at the edge of the open pit, then climbed down in it, partially disappearing from view, and wailed.

He remained there for at least a minute, his grief overwhelming other cries and prayers. Relatives and guards were unable to coax him out, but two men locked their arms underneath Karzai's and pulled their leader out by force.

As Karzai left, his phalanx of guards again powering through the masses, a stream of people dropped fistfuls of dust on the casket.

Ahmad Nadeem  /  Reuters

Afghan President Hamid Karzai looks down at the grave of his brother, Ahmad Wali Karzai, during his burial ceremony in Kandahar province, Wednesday.

Wali Karzai's death will transform power relations in the south, where the international military coalition has few friends of stature and none with the sweeping influence of the president's powerful sibling. Karzai will struggle to find an ally resourceful enough in balancing alliances with tribal and political leaders, drug runners and militias in a province where the Taliban still hold much sway.

The assassin was from Wali Karzai's tribe and hometown and traveled with and worked beside him for seven years.

Afghan officials said it's not clear whether he was killed by insurgents, as the Taliban claimed, or died as the result of an internal dispute.

Taliban spokesman Zabiullah Mujahid issued a statement Wednesday saying that insurgent fighters killed Wali Karzai because he cooperated with U.S., British and Canadian forces in the south.

"He was aligned with foreign occupiers," who bombed Afghan villages, Mujahid said.

The Taliban spokesman called Wali Karzai a "puppet" of the West and alleged that he was on the CIA payroll and profited from the illegal seizure of government and private land.

Wali Karzai had denied working for the CIA or being involved in shady business dealings.

Mujahid warned that if other Afghan officials fail to support the insurgency and befriend those aligned with the Afghan government and U.S.-led coalition, they will face the same fate as the slain Wali Karzai.

In Wednesday's insurgent strike in the eastern Kapisa province, an attacker detonated a bomb near a meeting of local leaders that was being guarded by French troops. Five French soldiers and an Afghan civilian were killed, the French president's office announced in Paris.

Four other French soldiers and three other Afghan civilians were seriously injured in the attack in the village of Joybar.

Afghan security forces were a conspicuous presence at the burial, with troops and intelligence agents dispersed around and within the crowd.

Despite heightened security, two members of the Afghan intelligence service traveling to Wali Karzai's funeral with Helmand provincial governor Gulab Mangal were injured when their vehicle struck a roadside bomb in Kandahar's Maiwand district, said Daoud Ahmadi, a spokesman for the governor of Helmand.

Rustam Shah, former Pakistan ambassador to Afghanistan, said Wali Karzai's death exposed the fragility of the security infrastructure in the southern provinces, particularly Kandahar where the Americans have boasted of progress in wresting territory from the Taliban.

"It will be a big blow to the government's image in the Taliban stronghold in southern Afghanistan," he said.

"The president will have to be very careful to move quickly to consolidate and maintain his power structure in Kandahar."