A suicide bomber killed least 20 people, including a member of parliament, at a funeral Sunday afternoon in a northern Afghan province that until now had been relatively secure.

Afghan officials said they believe that the lawmaker, Abdul Mutalib Baig, was the target of the bombing. Baig, they said, was a prominent commander of forces who fought against the Taliban in the 1990s, during Afghanistan’s civil war.

“We lost one of the great jihadi commanders,” said Haji Fareed Zaki, deputy governor of Takhar province, where the bomber struck shortly after 2 p.m. An 8-year-old boy was among the dead in the village of Taloqan, the capital of Takhar province. Dozens were reportedly wounded.

The village is in an area that is home to mostly ethnic Uzbeks and Tajiks and has seen a spike in attacks this year, as Taliban commanders have lost ground in their southern strongholds.

Afghan President Hamid Kar­zai said the bombing of “innocent people who had gathered for a religious ceremony yet again demonstrates the vile and vicious nature of the enemy.”

No group claimed to have carried out the attack, but Zaki said Afghan officials suspect the Taliban.

A statement from the U.S. Embassy also blamed the militant group and accused it of “waging a murderous campaign against Afghan innocent civilians, including women and children.”

The embassy said the attack “exposes as false” statements by Taliban leader Mohammed Omar that his group does not target civilians in violent attacks.

The bombing came a day after Karzai said that continuing night raids by NATO troops were hindering negotiations over a bilateral agreement between Kabul and Washington that would outline a legal framework for the continued presence of U.S. troops in Afghanistan after 2014.

“Arbitrary operations and house searches have . . . become one of the main obstacles for signing the Afghanistan-U.S. strategic partnership pact,” Karzai said in a statement. “As long as the night raids and house searches are not ceased, the documents will not be signed.”

U.S. commanders have defended their reliance on night raids, which they say are designed to minimize the potential for civilian casualties. They say such operations are increasingly being conducted alongside Afghan forces and, in some cases, led by Afghan troops.

Special correspondent Sayed Salahuddin contributed to this report.