UNITED NATIONS, July 31 (Xinhua) -- UN Secretary-General Antonio Guterres on Wednesday condemned the attack on a bus traveling a highway in western Afghanistan, which killed at least 34 people.

The secretary-general reiterated that international humanitarian law explicitly prohibits indiscriminate attacks that direct against civilians and appeals to all parties to the conflict in Afghanistan to uphold their obligations to protect civilians, his spokesman Stephane Dujarric said at a press briefing.

Guterres expressed his deepest sympathies to the families of the victims and to the government and people of Afghanistan, and wished a speedy recovery to those injured, Dujarric said.

Earlier Wednesday local time, at least 34 people were killed and 17 others wounded in a long-distance bus crash in Afghanistan's western Farah province, a local official confirmed.

"The accident occurred following an explosion when a pressure-plate landmine struck the ill-fated bus, causing it to veer off road and overturn along a main road in Aab Khorma locality of Farah Wednesday morning," the provincial official told Xinhua anonymously.

The official blamed Taliban militant group for planting the landmine on the roadside.