LAHORE (Reuters) - The Pakistani authorities on Friday (Sept 16) said they had arrested four militants of the Islamic State in Iraq and Syria (ISIS) plotting attacks in the city of Lahore, just weeks after the military declared it had halted the Middle East-based movement's expansion into the country.

The four were plotting attacks on government targets when they were seized in a raid along with 1.6kg of explosives as well as fuses and detonators, the city's Counter Terrorism Department said in a statement.

"The terrorists had planned to kill officials on a large scale" and were about to launch their attack when agents acting on a tip raided their hideout near Lahore's Moon Market, the department said.

It identified those arrested as Abdul-Alam, Muhammad Hafeez-u-Rehman, Nisar Ahmad and Tassavur Amin but gave few other details, including the day of the raid or how the men were identified as affiliated with ISIS.

Pakistan's military this month declared that it had foiled ISIS' attempts to establish operations in the country, saying it had arrested more than 300 militants and sympathisers including all but one of 20 core organisers.

"They tried to make an ingress, and they failed and they have been apprehended so far," military spokesman Lieutenant-General Asim Bajwa told reporters on Sept. 1.

Concern has been growing that ISIS - which controls parts of Iraq and Syria and is known for especially brutal treatment of religious minorities - might replicate their model in Pakistan, especially after ISIS loyalists seized small pieces of territory in neighbouring Afghanistan.

Those worries increased after the official ISIS news service claimed responsibility for a suicide bombing at a hospital in the Pakistani city of Quetta that killed 74 people.

The Quetta bombing, however, was also claimed by a breakaway faction of the Pakistani Taleban, Jamaat-ur-Ahrar, also believed to have carried out an Easter Sunday bombing that killed more than 70 people in Lahore.

Most ISIS recruits in the region are believed to be Pakistani or Afghan defectors from other Islamist movements.

Pakistan is home to several militant groups including the Afghan and Pakistani Taleban, Al-Qaeda and the Haqqani network, giving ISIS both a rich pool of potential recruits but also fierce competition.

ISIS last year declared Afghanistan and Pakistan as the state of "Khorasan", part of its self-declared global caliphate, and appointed longtime militant Hafiz Saeed Khan as its regional leader.

A US drone strike killed Khan last month in eastern Afghanistan.