IT is the suburban police zone under siege.

Officers in Sydney’s western suburbs are being ­repeatedly threatened, followed home from work and even watched by drones as they fight the rising threat of extremism in the area.

Police sources said there had been up to 30 threats made against the Merrylands squad and individual officers based in the western suburbs over the past year.

It included one threat to “shoot up” the ­Merrylands station in December.

Both male and female officers have also reported being followed home from the Memorial Ave station by people believed to be connected to local crime suspects.

Sources said unidentified drones were also seen hovering over the station on at least two occasions last year, sparking investigations which failed to find the controllers.

The Merrylands officers are ­believed to be targets because of their work in policing Middle Eastern ­organised crime in the area, including monitoring local terror suspects.

Some Sydney homes were raided last year after threats were posted on Facebook about gun attacks on the Merrylands police station.

The threats were traced back to a house less than one kilometre from the station, but no changes were laid.

media_camera Unidentified drones have been seen flying over Merrylands police station, where a number of threats by criminals have been made. Picture: Jonathan Ng

A NSW police spokeswoman confirmed there had been 20 to 30 threats to stations in the western suburbs and that police had been followed home but the incidents were not necessarily terror related.

She said any threat was “a major concern” and all stations were operating on heightened alert.

“The NSW Police force continues to operate under the Alert 2016 ­concept of operations, with all officers being reminded to maintain heightened levels of operational readiness and awareness both on and off duty,” a spokeswoman said.

“Any threat to police officers or police premises is of major concern and taken extremely seriously.” she said.

“However, it is not appropriate for us to ­discuss any specific information.”

media_camera The Middle Eastern Organised Crime Squad has conducted a number of raids in the Merrylands area.

The December threat to Merrylands station came just two months after the squad received a letter warning that “thousands will die” and threatening violence against non-Muslims, including at Jewish schools and NSW police stations.

It was reportedly accompanied by a photo of an Islamic State extremist with a row of severed heads spread in front of him.

The letter was understood to have been received a week after a teenage schoolmate of Parramatta police headquarters Islamic assassin Farhad Jabar was charged for posting allegedly inflammatory posts about ­Merrylands police.

The teen specifically mentioned Merrylands police in writing “Merryland (sic) Police Station is next hope they all burn in hell” on his Facebook page.

Jabar, a 15-year-old schoolboy, shot police employee Curtis Cheng, 58, in the back of the head as Mr Cheng left work at the Parramatta headquarters in ­October last year.