At least three persons were killed and 15 injured in a grenade attack on a church in the Pakistani town of Daska, about 70 km northwest of Lahore, on Wednesday night.

The police said the assailants have not been identified yet, adding that the attack on the Protestant church was under investigation.

No one has taken responsibility for the attack, which has prompted the civil administration in the town situated in the Punjab province to tighten up security.

The attack came hours after the police had announced that they found explosives and ammunition near a heavily guarded church in Islamabad.

Pakistani security officials said they found a shopping bag in bushes containing two handmade grenades and 20 shell casings about 100 metres from the St Thomas's Protestant Church.

There have been four deadly attacks on Christians in Pakistan this year. The last was on September 25, when gunmen entered the offices of a Christian welfare organisation in Karachi, tied seven employees to their chairs and shot each in the head.

On March 17, a grenade attack on Protestant church in Islamabad killed five people, including a US Embassy employee and her 17-year-old daughter.

On August 5, assailants raided a Christian school filled with foreign children in Murree, 65 km east of Islamabad. Six Pakistanis were killed, including guards and non-teaching staff.

On August 9, attackers hurled grenades at worshipper at a church on the grounds of a Presbyterian hospital in Taxila, about 40 km west of Islamabad, killing four people.