Two accused of Oxford St punch-up

A good samaritan who intervened in a fight at a notorious Sydney party strip has been punched to the ground, police say.

It is alleged two men, aged 21 and 22, were leaving a fast-food restaurant on Oxford Street about 3.15am (AEDT) on Sunday when they allegedly punched another man.

Police closed in but the 22-year-old allegedly then punched a 25-year-old passer-by who tried to assist officers, knocking him to the ground.

The injured man was treated for a head laceration but did not need to go to hospital.

Police say they have charged the 21-year-old with affray and released him on strict bail ahead of a Downing Centre Local Court appearance on February 28.

The 22-year-old was charged with assault occasioning actual bodily harm and affray.

He remains in custody as he awaits an appearance at Parramatta Local Court on Sunday.