A Royal Navy sailor groped a female colleague on board a warship after a drunken night out while docked in Bahrain, a court martial has heard.

Leading Seaman (Marine Warfare) Lee Roberts, stationed at Portsmouth Naval Base, denies the offence of sexual assault which is alleged to have taken place on board the Clyde-based minehunter HMS Ramsey.

Major James Thomas, prosecuting, told the Portsmouth court martial that the 34-year-old, who had been serving aboard HMS Atherstone, another minehunter, had met a friend while out for the night in Bahrain on June 26 last year.

The friend had invited him back to the senior rates mess, a common room for sailors, on board HMS Ramsey where the defendant sat next to the alleged victim, who was wearing denim shorts and a T-shirt.

Maj Thomas said: “They had both been out that night, albeit not together, they did not know each other at all. The defendant was sat next to her, there was no flirting between them, no indication they were interested in each other.

“After a time, LS Roberts leaned over her and placed his hand on her groin, over her shorts. She grabbed his hand, asked what was he doing and shouted he had touched her. He denied he had done anything wrong and left.”

Maj Thomas said that the victim had complained about his actions immediately and had no motive to make up the allegation.

He said: “The complaint could not have been more immediate, it was instantaneous and unequivocal. If not telling the truth, she must have had some motive to lie, she must have made up her mind to write a complaint against a man she had never met before and had no axe to grind. The defendant said he was not near her and didn’t touch her.”

Maj Thomas told the panel of senior officers, which act as the jury in court martials, that several of the witnesses had been drinking that night and this had affected their recollection of the events.

The victim told the court that she had gone out with a group of friends to a restaurant followed by a bar and had she had consumer about 10 drinks, mostly cocktails, during the evening before returning to HMS Ramsey at about 1.55am.

She said: “I was in high spirits but I was aware of my surroundings.”

The sailor, who has since left the navy, said that she went to the senior rates mess with some of her friends when the defendant, who was talking to a mutual friend, sat next to her.

She said: “Everyone was just talking and then at some point he touched my groin area, he just leaned over with his arm and touched me. I immediately pulled it away.

“Afterwards I said ‘Get off, what are you doing?’ and if I remember he found it funny, just laughing.

“I can’t remember exactly what I said, I think I said ‘You are disgusting’ and ‘What would you do if that happened to your child if you have children?’ and he said ‘Yes’.

“I left then, I went for a cigarette then I went to bed.”

She said that she informed a petty officer the following day about the incident which led to it being investigated by the police.

The case continues.