Updated

A bomb planted in a graveyard in rural eastern Afghanistan killed 14 members of a single family on Thursday as the country's president urged the Taliban to lay down their arms.

The attack took place in Nangarhar province's Ghany Khel district and all 14 killed -- seven women and seven children -- were members of the same extended family, said Masum Khan Hashimi, the province's deputy police chief. Three family members were also wounded in the attack, he said, adding that an investigation was underway.

The family gathered to mark the start of a major Muslim holiday, the Eid al-Fitr at the end of the holy month of Ramadan, with a visit to the tomb of a relative. In Afghanistan, it is customary for families to visit the graves of loved ones on holiday occasions.

No group immediately claimed responsibility for the bombing.

The dead man's brother, Haji Ghalib, who said his daughter was among those killed Thursday, blamed the Taliban for the attack. Ghalib, who was not with his family when the bombing happened, said over the telephone that he also worked at a security company and was a member of a local peace council seeking to reconcile with the insurgents.

"My family is finished. These people are inhuman," he said.

President Hamid Karzai condemned the bombing, denouncing it in a statement as "a cowardly act by the enemies of the people of Afghanistan who are not part of any religion."

"They even attack in a Muslim cemetery on the start of Eid, they kill our innocent countrymen," Karzai said.

Earlier, in a speech after attending prayers in Kabul for the holiday, Karzai urged the Taliban to lay down their arms, join the political process and stop killing innocent civilians.

Mashoq Malam, the chief official in Ghany Khel district where the bombing occurred, said it was unclear why someone had planted the remote-controlled bomb at the graveside of the family. The deceased man had worked for a security company and was killed about eight months ago by the Taliban, Malam said.

"These cruel people who don't respect God or Islam and planted a mine on a grave," he angrily said in a telephone interview. "As soon as the poor women and children gathered by the grave, it exploded."

A spate of bombings and Taliban attacks in Nangarhar in recent weeks has killed dozens of people, including police and security forces. Among the attacks was a botched bombing last week against the Indian consulate in the city of Jalalabad that killed nine people, including six children. No Indian officials were hurt.

In his holiday address, Karzai said that too many Afghans have lost their lives to roadside bombs during this year's Ramadan.

"Tens of our innocent Afghans, including mothers and sons, died by the mines planted on the roadsides by the enemy," he said. "From one side of Afghanistan to the other, people gave their lives because of the mines and terrorist activity."

He urged the Taliban to stop fighting and killing fellow Afghans.

"Serve your country and leave the weapons that you get from the foreigners to kill your people. Instead of a gun, pick up the shovel and spade and serve this country," Karzai said, alluding to Afghan charges that the Taliban are sheltered and equipped in the lawless tribal areas of neighboring Pakistan.

According to the United Nations, Afghanistan's civilian casualty toll has jumped this year as insurgents fight to recapture territory from the departing American-led coalition.

Karzai also said Thursday that the Taliban should, instead of opening an office in the Gulf state of Qatar, open one in Afghanistan, just like any other political party. The Taliban opened a political office in June to facilitate talks with the U.S. and the Afghan government.

But those talks foundered before they even began when the Taliban marked the opening with the flag, anthem and symbols of the Islamic Emirate of Afghanistan -- the group's name when they ruled the country. Karzai immediately pulled the plug on talks saying the office had all the trappings of an embassy of a government in exile.

Taliban leader Mullah Mohammad Omar has ruled out participating in the political process while Karzai remains in power. In his own Eid message earlier in the week, Mullah Omar called on Afghans to boycott the April 5 presidential elections next year, calling them "a waste of time." Karzai constitutionally cannot run for a third five-year term.

Mullah Omar said, however, that the Taliban were still willing to restart talks.