Melbourne teen punches disabled man in the face

A teenage girl has been arrested after footage of her punching the face of a young disabled man was posted online.

The disturbing attack took place at Pakenham, south east of Melbourne, last Friday, the Daily Mail reports.

In mobile phone footage of the incident, the special needs student, 18, can be seen sitting on a turned over blue shopping trolley when the teen approaches him.

The girl, wearing a t-shirt and shorts, pummels the man's face with two punches, forcing him backwards and appearing to knock him out.

As the man slumps over showing little movement, the girl walks away checking her knuckles to cheers from her friends.

The teen, who has not been named, has since taken to Facebook to explain her actions.

She claims the man threatened her and her friends and that he asked her to punch him.

She said everyone at the park "wanted to do it but didn't have the balls".

"If it wasn't me it would have been the boys and they would have done worse than that," she said.

"I have already spoken to (the man) about it and he was asking me to punch him because he didn't think he would feel it."

The teenage girl is expected to be charged with reckless conduct causing injury and assault.