At least 22 people, including five children and as many women, were killed and several others injured on Wednesday as a van they were travelling in fell hundreds of feet into a ravine in Pakistan's mountainous Balochistan province, an official said.

The vehicle, with approximately 23 people on board, plunged into the ravine when the driver apparently failed to negotiate a sharp bend in the mountainous area of Akhtarzai near Killa Saifullah, which is at an elevation of 1,572 metres.

Deputy Commissioner of the Zhob district, Hafiz Muhammad Qasim, said that the passenger bus was travelling to Zhob town from Loralia.

"The vehicle fell from a hilltop near Akhtarzai. We have recovered all the bodies despite rescue operations being difficult due to the deep ravine in the mountains, he said.

The official said that the deceased include five children, five women and 12 men.

A child, who survived the accident, was rushed to a nearby hospital, Qasim said.

An alert has been sounded at nearby hospitals and teams from Quetta were called in to aid the rescue operation, he said.

Condolences started pouring in after the accident.

Balochistan Chief Minister Mir Abdul Qudoos Bizenjo condoled the loss of lives and instructed the authorities to provide the best medical treatment to the injured child, the Dawn newspaper reported.

Foreign Minister Bilawal Bhutto Zardari expressed grief over the accident and urged authorities to ensure adequate medical treatment for the injured, calling on them to take steps to avoid such accidents in the future.

The Pakistan Peoples Party said on Twitter that Bilawal has extended sympathies to the bereaved families.

Every year, road accidents claim hundreds of lives in the country's restive Balochistan province due to the difficult and hilly terrain.