Police have extradited a 28-year-old Nowra man for a second time after he failed to appear before court on a child sex offence charge.

The man had been arrested in December after allegedly sexually assaulting a child known to him.

Police say he was charged with committing an act of indecency on a child under 10 and bailed to appear before court in June.

After he failed to appear, a warrant for his arrest was issued. He was arrested in Nowra and extradited to the ACT on August 12 to face the ACT Supreme Court.

He was again provided court-issued bail, to next appear in September. He again failed to attend, and the court issued a second arrest warrant.

With assistance from NSW police, the man was arrested in Nowra on Tuesday and extradited to the ACT.