A Royal Navy sailor who was found dead from a fatal dose of heroin while taking part in a drugs operation overseas was probably “injected by a third party”, an inquest has ruled.

Charles Warrender, who was serving on the HMS Richmond in the Indian Ocean, was found dead barefoot with his shoes and socks placed next to him in the Seychelles.

His body was discovered behind the national library in the island’s capital, Victoria, on 30 May last year and his money had been stolen.

Local police said there was no evidence of foul play but his inquest heard that Warrender, whose ship was on a mission to disrupt the drug trade, was found with high-grade heroin sprinkled on his chest.

The inquest also revealed that the engineer technician had no history of drug taking and had a phobia of needles.

But despite ruling the dose was “likely” to have been administered by a third party, the coroner for Grimsby and North Lincolnshire, Paul Kelly, did not record a verdict of unlawful killing.

Kelly said Warrender would be aware that his Royal Navy career would be in jeopardy if he tested positive for drugs.

The coroner said he relied on the evidence of the renowned forensic pathologist Dr Nathaniel Cary and said “he could not exclude the possibility the fatal dose was administered by a third party”.