A man drowned after he disappeared during a stag weekend in Prague which involved heavy drinking and taking cocaine, an inquest has heard.

Karl Law had travelled to the capital of the Czech Republic with a group of 12 friends and family to celebrate the forthcoming marriage of his cousin Lee Cross.

But after a night visiting bars and clubs, the 34-year-old walked off alone in the early hours of November 16 last year and was not seen alive again by the group. He is believed to have been sighted by a local at 11pm the following night.

The family launched a massive search for Mr Law, a builder from Fareham, putting up missing posters and running appeals on social media, in local papers and on TV.

The Portsmouth inquest heard his body was found in a state of undress and covered in algae on December 7 in the city's Vltava River, close to the Jiraskuv Bridge.

He was identified by his uncle and through DNA tests.

A post-mortem examination carried out by the Czech authorities showed he had died of drowning about three to four weeks earlier and he had no injuries or signs of being attacked.

Toxicology tests showed he had a large amount of alcohol in his system as well as medication taken for depression.

The inquest heard the anti-depressants found in his blood may have been cut into the cocaine he had been taking as he was not known to have been prescribed the medication.

Detective Sergeant Steve Toms, of Hampshire police, said Mr Law, a keen angler, was believed to have drunk about 10 half-litre glasses of lager during the night before he disappeared as well as absinthe, and he had also taken seven lines of cocaine.

He said Mr Law had shown ''irrational bouts of paranoia'' and had at one point broken his mobile phone up before biting the Sim card in two because he believed it might be traced by the police.

Mr Toms said: ''This was due to his fear of being caught with drugs on him.''

He said Mr Law's family believed he had no mental health issues but had been upset at the death of his best friend from cancer two years previously as well as the death of the friend's daughter just prior to the trip.

Mr Law's brother Craig said: ''He didn't seem any different to how he normally is, I knew he was a bit paranoid, he has always been paranoid, to be fair, just worried about things I suppose.''

He said he spent four weeks in Prague searching for his brother, putting up posters and scouring the streets.

Friend Eugene Small, who was the last to see Mr Law alive, described him as ''a bit eccentric''.

He said: ''No-one disliked Karl, a lovely bloke, he dressed a bit eccentric, always had one sock different to the other.''

Mr Law's fiancee Amanda Collins, who is the mother of their young son Lenny, described him as a ''fun-loving family man''.

David Horsley, coroner for south-east Hampshire, recorded a verdict of accidental death.

He said: ''He was having a good time in the way the rest of the party was. There's nothing to suggest he was getting overly depressed by the death of his friends.

''Whatever happened, I do not believe he has deliberately taken his own life, there's nothing to suggest that.''

He continued: ''So what has happened to Karl? It is something of a mystery, he has been doing what everyone else has, I do not think he was in any worse state than anyone else, but coming out of that last club he has gone off in a different direction than the others.

''I think he has probably fallen into the river and because he was intoxicated and not a strong swimmer he has been unable to save himself. That would have happened quickly, it was winter, it was cold, he would probably have passed out before he died.''