Detectives have renewed their appeal for public assistance as they investigate an armed raid on a credit union at Murwillumbah, on the NSW-Queensland border, late last month.

About 4pm on Monday 30 May, a man entered the Commercial Road branch and threatened staff with a sawn-off shotgun.

He stole a sum of cash before fleeing along the western bank of the Tweed River, which runs behind the credit union.

No shots were fired during the incident and no one was injured.

Police from Tweed/Byron Local Area Command responded quickly to the incident; however, a search of the area failed to locate the offender.

Local detectives have been conducting extensive inquiries into the incident.

They have now released closed-circuit television (CCTV) images of a man they believe might be able to assist with their inquiries.