Abandoned NSW school building catches fire

A derelict school building has caught fire in Sydney's west.

The blaze started in the roof of the abandoned Macquarie Boys' High School building on Kissing Point Road, Parramatta, just before 4pm Saturday.

A NSW Fire and Rescue spokesman said crews noticed large volumes of smoke en route to the scene and called for backup before they arrived.

The second level of the building was well alight.

About an hour after emergency services were called, there were 10 fire trucks and 40 firefighters trying to extinguish the blaze.

There were no evacuations and no reports of any injuries, the spokesman told AAP.

Crews had gained the upper hand by 4pm but firefighters expected to stay at the scene for "some time", NSW Fire and Rescue said.

It's not the first time the site has been damaged by fire - a blaze in late July 2016 destroyed the school hall and while police treated the blaze as suspicious, nobody was charged.

Last year's incident sparked questions about the future of the site, which became a haven for vandals after it was closed in 2009 due to falling enrolments.