A fire ripped through a nightclub popular with foreign tourists on the Thai resort island of Phuket early on Friday, leaving at least four people dead and more than 20 others injured, officials said.

Foreigners were among the party-goers hurt in the blaze at the Tiger disco on the southern island, where rescue workers pulled the charred bodies of victims out of the smoldering wreckage.

"There are four confirmed dead. We believe they are foreign tourists but it's not yet confirmed," Phuket deputy governor Chamroen Tipayapongtada told AFP by telephone.

Hospital workers in the seaside resort of Patong said the injured included both Thais and foreigners.

"We received more than 20 people who sustained injuries from the Tiger Pub fire. Most are suffering from suffocation," one hospital employee said.

"Two are in critical condition from severe burns. One of them is a French man who suffered burns on his torso," she added. "The four dead bodies were burnt beyond recognition. We cannot identify even their gender."

A team from the National Police Office was on its way to Phuket to try to identify the four people killed in the fire, which is believed to have broken out at about 4:00 am (21:00 GMT on Thursday) and was extinguished at around dawn.

Outside the blackened remains of the nightclub, much of which was destroyed by the blaze, police kept back a crowd of onlookers as ambulances arrived to collect the casualties.

Police said initial indications suggested a lightning strike or an exploding electrical transformer could have sparked the fire.

"Witnesses said there was a power blackout and it was raining. When the power came back they heard a loud explosion and the fire broke out," said Police Colonel Chirapat Phochanapan in Phuket.

Tomrongsak Boonyarunk, an executive with the Tiger Group which runs the nightclub, told AFP that the venue was officially closed at the time of the fire but about 70-80 people were still inside sheltering from heavy rain.

"What happened is a force majeure. There were up to three lightning strikes and blackouts before the fire broke out".

"We fully comply with the law on fire exits," he added. "We will not duck responsibility. We are sorry. I've sent staff to hospital to look after the injured people."

Concerns about fire safety at Thai nightclubs were highlighted by a massive blaze at a disco in the capital Bangkok in 2009 that left more than 60 people dead, including foreigners, as people celebrated the new year.

In that incident hundreds of party-goers were inside the Santika Club when it was set ablaze by pyrotechnics during a performance by a rock band

Three Singaporeans, one Japanese and a Myanmar national were among the dead, while scores of foreigners including some from Australia, France and Britain were injured.

Last year the owner was convicted of gross negligence and sentenced to three years in prison.

Thailand is a tourist magnet but its image as the 'Land of Smiles' has been tested in recent years by deadly political unrest, devastating floods and concerns about violent crimes against foreigners.

In June an Australian woman was stabbed to death during an attempted robbery in Phuket, and two Canadian sisters were found dead in a hotel room on nearby Phi Phi island, showing signs of an extreme toxic reaction.