Two men have been bashed and robbed by a group who responded to an online ad for a mobile phone.

At about 7.30pm, a man went outside his Merrylands unit to meet a person who had responded to his online ad for the phone.

When he saw three men, the 30-year-old became worried and went back inside.

He gave the phone to one of his housemates and left the property.

The group of men didn’t leave though, instead knocking on the door and then forcing their way inside the unit.

The allegedly assaulted two of the residents, aged 20 and 29, before stealing two mobile phones and a laptop and fleeing the scene.

The two residents were taken to Westmead Hospital with concussions while forensic specialists examined the property.

The three assailants are still on the run and have been described as African in appearance.