A Bristol warehouse manager man who died after a robbery in Avonmouth was assaulted before he collapsed, detectives have revealed.

Senel Mansiz, 30, died from a condition called an aortic stenosis, which means his heart suddenly stopped.

And it has today emerged that he collapsed after five men robbed M and M Catering Supplies in St Andrew's Road, where he was the night manager.

Police say they're treating it as a murder investigation because the death occurred immediately after the robbery and is related to it.

Detectives have released a picture of Mr Mansiz along with CCTV footage of the robbers entering the premises.

The men are seen wearing hooded tops with Halloween-style masks over their faces. One of them is carrying what looks like some sort of club.

Detective Chief Inspector Garry Reeves, who is leading the murder investigation, said: "I'm appealing to anyone who recognises or knows these men to contact us.

"And I'm appealing directly to the robbers themselves. I have seen the complete CCTV footage of what happened inside that office, and I urge them to come forward and help us."

Two men aged 22 and 24 have been released on police bail. A third man, aged 27, remains in custody for questioning.

Turkish-born Mr Mansiz, who worked as a night manager, lived in Lawrence Weston with his wife.

Paramedics and police were called to the firm's cold storage premises at 7.45pm on Thursday and he was pronounced dead at the scene.

M&M Catering supplies doner kebabs, burgers and pizza bases to the food industry along with sauces, food boxes and cutlery.

Police have repeated their appeals for witnesses. They would like to hear from anyone who was in the St Andrew's Road area in Avonmouth at the time of the incident – about 7.30pm on Thursday evening.

They especially want to speak to anyone who saw a black Audi saloon which may have been driven around the St Andrew's Road area on Thursday evening or for several days before the raid.

Anyone able to help the inquiry is asked to contact Bristol CID on 0845 4567000. Alternatively you can contact Crimestoppers on 0800 555111.