ISLAMABAD, March 28 -- Pakistani security forces have launched operations in parts of eastern Punjab province where a suicide bomber killed at least 72 people and injured 315 others at a crowded park, the army said Monday.

A Pakistani Taliban splinter group "Jamaat-ul-Ahrar" claimed responsibility for the attack in Lahore Sunday evening and its spokesman said minority Christians were its target. Christians were at the park to celebrate Easter.

Police officials, however, said 44 were Muslims among those killed.

The security forces conducted operations in some major cities in Punjab hours after the blast.

"Intelligence agencies with Army ¶military 'Rangers' carried out 5 operations in Lahore, Faisalabad and Multan in Punjab since last night. Operations continue with more leads coming in," the army spokesman, Lt. Gen. Asim Bajwa said.

"A number of suspect terrorists and facilitators arrested and huge cache of arms and ammunition recovered," he said in a statement.

The army chief, Gen Raheel Sharif, presided over a high level security meeting to review progress of operation in Punjab to nab terrorists in the aftermath of Lahore blast, the spokesman said.

Separately Prime Minister Nawaz Sharif also chaired a meeting to review security after the deadly terrorist attack in the relatively peaceful city.

Official sources told the media the meeting agreed to take action against the "suspected facilitators" of the militant groups.

The prime minister, who postponed his visit to London, also visited a main hospital Monday morning and inquired about their health. Sharif was scheduled to leave for London on Monday for his onward journey to Washington where he will represent Pakistan in a nuclear summit. He will now leave for Washington after two days.

Mourning day is being observed across the country against the Lahore suicide attack. The national flag is flying at half-mast at all the government buildings.