Man charged after gel blaster found on train in Sydney's inner south

A man has been charged after a gel blaster was found on a train in Sydney's inner south.

Police were called to Redfern Railway Station after the "firearm" was found on the seat of a train as it was going through Sydenham about 8.10am.

"Police were told a man had been sitting alone on a seat after boarding the train about 7.45am at Allawah," NSW Police said in a statement.

READ MORE: How a startling discovery from a DNA test led an Australian adoptee to his birth family

"The firearm was seen shortly after the man left the train at Sydenham and passengers alerted rail staff, who called police."

Officer arrested a 43-year-old man at a home in Carlton at 3am.

He was charged with entering or leaving a restricted area without a ticket and possessing an unauthorised prohibited firearm.

He was refused bail and is due to appear in Sutherland Local Court today.

Gel blasters are life-like toy guns that are designed to shoot water-based pellets.

They are illegal in NSW.

"There is no genuine reason to possess or use a Gel Blaster in NSW," police said on their website.