Pakistani Christians search for relatives at a hospital in Peshawar.

Pakistani Christians search for relatives at a hospital in Peshawar. Photo: AFP

Two suicide bombers have killed at least 61 people and wounded more than 100 attending a church service in restive north-western Pakistan.

The Sunday attack in Peshawar is one of the deadliest for years on Christians in the overwhelmingly Muslim country.

The death toll was given by Doctor Sher Ali, deputy medical superintendent of the city's main Lady Reading Hospital.

Peshawar's commissioner Sahibzada Anees told reporters the bombers struck as the service ended.

"Most of the wounded are in critical condition," he said, adding special security had been in force to protect the church.

"We are in an area which is a target of terrorism and within that area there was a special security arrangement for the church."

Schoolteacher Nazir Khan, 50, said at least 400 worshippers were greeting each other when there was a huge explosion.

"A huge blast threw me on the floor and as soon as I regained my senses, a second blast took place and I saw wounded people everywhere," Mr Khan told AFP.

Television footage showed ambulances rushing the wounded to hospital.

Grieved relatives gathered outside the church and shouted slogans against police over the security lapse.

Pakistani Prime Minister Nawaz Sharif strongly condemned the bombings.

"Terrorists have no religion and targeting innocent people is against the teachings of Islam and all religions," he said in a statement.

Sharif said such "cruel acts of terrorism reflect the brutality and inhumane mindset of the terrorists".

He expressed his solidarity with the Christian community and deep sympathies with bereaved family members.

Only two per cent of Pakistan's population of 180 million are Christian. The community is largely poor and complains of increasing discrimination.