Protests are taking place in the eastern cities of Lahore, Faisalabad, Sargodha and Gujranwala.

The authorities are appealing for calm after an angry mob lynched two people suspected of involvement in the attack.

A Taliban splinter group has said it carried out the attacks, the worst on Pakistan's Christians since 2013.

Christian missionary schools around the country are closed as Pakistan observes a day of mourning.

Christians make up a tiny fraction of Pakistan's overwhelmingly Muslim population and are vulnerable to sectarian attacks.

Pakistan's Christians

Make up 1.6% of Pakistan's predominantly Muslim population

Majority are descendents of those who converted from Hinduism under the British Raj

Most converted to escape their low-caste status and many are among the poorest in Pakistan

Targeting of Christians fuelled by strong anti-blasphemy laws and anger over US-led war in Afghanistan

The BBC's Shaimaa Khalil, in Lahore, says the mood is tense and sombre inside the Youhanabad area - the city's largest Christian neighbourhood - where the attacks took place.

Adults and children have been carrying crosses and raising banners saying "Stop killing Christians" as they marched towards St John's Church and Christ Church, the scenes of Sunday's blasts.

Local media showed pictures of the crowd in Youhanabad throwing rocks at passing cars, smashing their windows.

There is a great deal of grief but also a great deal of anger, our correspondent says, as Christians in Lahore feel they have regularly been targeted by extremists and abandoned by their government.

"We are proud to be Christians here but the way we are treated... is beyond our understanding," Arcene Anthony, a sister at St John's, told the BBC.

Interior Minister Chaudhry Nisar Ali Khan called the assaults "an inhuman act of terrorism".

Attacks against Christians in Pakistan are not uncommon, analysts say. Some are related to Pakistan's controversial anti-blasphemy laws.

But this is the first large-scale attack on the community since 22 September 2013, when the bombing of a Peshawar church killed more than 120 people, in what is thought to be the deadliest attack on the country's minority