LAHORE (Pakistan) • The Pakistani authorities launched a paramilitary crackdown in Punjab province to hunt for Jamaat-ul-Ahrar militants from the breakaway Pakistan Taleban who have claimed responsibility for the Easter suicide bombing at the Gulshan-e-Iqbal park in Lahore on Sunday.

Since Sunday night, several suspects have been arrested in raids in Lahore, Faisalabad and Multan in Punjab where a huge cache of arms and ammunition was recovered.

The militants had been targeting Christians, killing at least 70 people in the playground blast, with children making up nearly half of the dead. Explosives packed with ball bearings ripped through crowds near a children's play area in the park where mostly women and children had gathered to celebrate Easter. Lahore's top administration official, Mr Muhammad Usman, said the bomber "blew himself up near the kids' playing area where kids were on the swings".

Arif Gill, 53, said: "We had gone to the park to enjoy the Easter holiday. There was a blast. Suddenly, I saw a huge ball of fire and four to six people of my family were injured, two of them critically."

Rescue spokesman Deeba Shahbaz said the toll had risen to 72 yesterday, with 29 children among the dead. About 340 were wounded, with 25 in serious condition.

Senior police official Haider Ashraf said most of the dead were Muslim.

Pakistan is a Muslim-majority state but has a Christian population of more than two million who have long faced discrimination.

Mr Javed Ali, a 35-year-old who lives opposite the park near the centre of the city, said the force of Sunday's blast shattered the windows of his home. "After 10 minutes, I went outside. There was human flesh on the walls of our house. People were crying, I could hear ambulances," he said.

Jamaat-ul-Ahrar, a faction of the Pakistani Taleban, claimed responsibility for the attack in Lahore, and issued a direct challenge to the government.

"The target was Christians," said a faction spokesman, Ehsanullah Ehsan. "We want to send this message to Prime Minister Nawaz Sharif that we have entered Lahore."

Mr Sharif expressed his "grief and sorrow over the sad demise of innocent lives". His Indian counterpart Narendra Modi said "the people of India stand with their Pakistani brethren in this hour of grief," state media reported.

Pope Francis yesterday condemned the Easter suicide bombing by Islamist militants as "a vile and senseless crime". "I appeal to the civil authorities and all sectors of that nation to make every effort to restore security and serenity to the population, and in particular to the most vulnerable religious minorities," said the Pope.

United Nations Secretary-General Ban Ki Moon also echoed the call for Islamabad to protect religious minorities.

Singapore's Ministry of Foreign Affairs said: "We are deeply saddened by this senseless act of terror, which killed and injured many innocent civilians, mostly women and children.

"We express our deepest condolences and sympathy to the families of the victims and the people of Pakistan.

"This heinous attack is a stark reminder of the threat we all face from terrorism, and the need for continued vigilance and determination in countering the threat."

REUTERS, AGENCE FRANCE-PRESSE