Gwent Police is appealing for information following a robbery at Gelligaer Post Office, Castle Hill on Monday March 8.
At 5.30pm a man entered the post office, threatened the postmaster with a metal bar and made off with a substantial sum of money.
The postmaster did not suffer any injuries.
Anyone with information, or anyone who may have seen any suspicious activity or vehicles at the time, should to contact police on 101 or call Crimestoppers on 0800 555 111.