UNITED NATIONS, June 16 (Xinhua) -- UN Secretary-General Antonio Guterres welcomed on Saturday the Afghan government's announcement of a unilateral extension of the ceasefire with the Taliban.

Speaking through his spokesperson Stephane Dujarric, Guterres urged the Taliban to heed the call for peace from the Afghan people and reciprocate the gesture.

He said he believes that the only solution to the conflict in Afghanistan is through an inclusive political process and urged both sides not to let those trying to derail the peace efforts to prevail.

The UN chief condemned Saturday's attack in the eastern province of Nangarhar targeting Eid celebrations.

At least 26 people were killed in the blast in Nangarhar, a provincial government spokesperson said.

The incident occurred in the afternoon when explosive materials in a Taliban vehicle detonated at a gathering on the outskirts of the provincial capital of Jalalabad.

Among the victims were Taliban militants, civilians and members of Afghan security forces.

The government announced a seven-day ceasefire from June 12 to encourage the Taliban to support the national reconciliation process.

Reciprocating the step, the armed group announced a three-day truce from the first day of Eid-ul-Fitr to the end of Sunday.

The ceasefire was extended Saturday unilaterally by the Afghan government despite the bombing, through a rare televised address by President Mohammad Ashraf Ghani.

Ghani asked the Taliban to extend their three-day ceasefire too but the group has not responded so far.