Gwent Police has released CCTV of the armed robbery at Ladbrokes betting shop on Commercial Street, Pontllanfraith.
The robbery happened at 8.20pm on Monday October 17.
Two men entered the shop armed with a shot gun and a knife and demanded money from the cashier. An undisclosed amount of cash was stolen and the two men made off.
No one was injured, although two members of staff were left shaken.
Detective Superintendent Paul Griffiths is leading a 20-strong dedicated team of officers who are continuing to investigate the incident.
He said: “We are following numerous lines of inquiry at present including looking at CCTV, making house to house enquiries in the local area and speaking to witnesses.
“I am re-appealing to anyone who may have seen suspicious activity in the area to come forward. If you think you recognise the two men in the CCTV from their shape, size and the style of clothing please get in touch. I would also ask that anyone who may know someone who has access to an illegal firearm to contact us.”
One of the robbers was described as wearing a blue hooded top with a small yellow square label on the rear between the shoulder blades, and blue cargo style trousers.
The second was described as wearing a green camouflage style hooded top and dark coloured tracksuit bottoms with three line fluorescent stripes down the side of the legs.
If the public see individuals fitting the descriptions given they are advised not to approach them, but to contact the police immediately or call Crimestoppers anonymously on 0800 555 111.