Oamaru police did not have to travel far to arrest a 22-year-old Oamaru man for assault on Monday.

In fact, they did not even have to leave the police station.

The unusual incident unfolded about 1pm when a man, also from Oamaru, walked into the station in Severn St in an effort to escape another man that was pursuing him over what was believed to be an unpaid debt.

The offender followed the victim into the station's foyer before he confronted him and allegedly punched him once in the face.

The man was promptly subdued, then arrested and charged with one count of assault.

He is scheduled to appear in the Oamaru District Court on August 15.

Sergeant Blair Wilkinson, of Oamaru, said police had little trouble piecing together the evidence that led to the man's arrest.

''It wasn't a particularly hard one to investigate.''