Police in Spain are searching for a Bulgarian man who was partying with Boyzone singer Stephen Gately shortly before his sudden death on the holiday island of Majorca.

The 33-year-old's body was found by his civil partner Andy Cowles in their STG1 million ($A1.75 million) apartment in the upmarket resort town of Port d'Andratx on Saturday after the pair had enjoyed a night out.

Some British media reports on Monday suggested Gately died after choking on his own vomit following an eight-hour drinking binge.

Spanish police say they do not believe the Irish singer's death to be suspicious but want to interview a 25-year-old Bulgarian man who was invited to the couple's apartment in the hours before the singer died.

"We do not think the man is involved in any way in Stephen's death but his testimony could prove vital," a Spanish police source told The Times.

A post-mortem is expected to be carried out on Gately's body on Tuesday.

The singer and his partner spent Friday night drinking in bars in the island's capital Palma before returning to their apartment in the early hours of Saturday morning.

They invited Bulgarian Giorgi Duchev, who they met in a gay nightclub, to join them.

The Sun newspaper reported that Cowles, 32, went to bed around 5.30am, leaving Gately asleep on a sofa.

When he woke around midday on Saturday he found Gately in a "prayer position", squatting on the floor with his head face down on a pillow on the sofa.

Cowles, who first met Gately at Sir Elton John's 60th birthday party, spent 30 minutes trying to revive Gately, but without success.

"The rest is a mystery," police sources told The Sun.

"There were no signs of violence or evidence of suicide or any obvious evidence pointing to another probable cause of death, like drugs use.

"But we're unlikely to be able to shed any further light on what's happened until after a post-mortem."

A family friend told The Daily Mirror: "The family have been told the most likely scenario is Stephen had a bit too much to drink, vomited in his sleep and choked. It was a terrible accident."

Gately's lawyer and family spokesman Gerald Kean said no foul play was involved.

"There is nothing untoward," he said.

"It's not drugs, it's not suicide, it's not murder, it's not a fight."

Gately's family hope his remains will be flown to Dublin by the end of the week for a funeral.

Gately's Boyzone bandmates - Ronan Keating, Mikey Graham, Keith Duffy and Shane Lynch - have flown to Majorca to comfort Cowles.

"We are completely devastated by the loss of our friend and brother, Stephen," they said in a statement.

"We have shared such wonderful times together over the years and were looking forward to sharing many more. Our love and sympathy go out to Andrew and Stephen's family. We love you and will miss you forever, 'Steo'."

The band's former manager Louis Walsh pulled out of Sunday night's live broadcast of hit TV talent show X Factor because he was too distraught over Gately's death.

"Stephen was one in a million," he said.

"He was the most grateful person, humble and modest. Andy is utterly devastated. He can't believe he is gone."

Sir Elton John also joined the tributes, saying Gately was "the kindest, gentlest soul", while rival Irish boyband Westlife said they were "in shock".

Boyzone formed in 1993 and went on to become one of the most successful boybands in music history.

The group had six number one singles, including No Matter What, and four number one albums, with sales of around 20 million.

The group split in 2000 but reformed in 2008 and had plans to release a new album and go on tour.