Gardaí have begun an investigation into a fire which broke out at a ’head shop’ in the centre of Dublin early this morning.

Nirvana, a store on Capel Street that sells so-called “legal highs,” was gutted in the blaze which led to the closure of the street to traffic for the day. The street will be closed until Monday at least.

The fire started at approximately 6am and quickly spread to two adjoining shops including the sex shop, Utopia 2.

Five units of the Dublin Fire Brigade attended the fire including units from Tara Street, Phibsborough and North Strand stations.

Initally there were fears the fire might spread to other buildings but firefighters were able to bring the blaze under control at about 11am However, it wasn’t fully extinguished until about 5pm.

There are no reports of anyone being injured although a number of residents living in nearby flats were evacuated.

Throughout much of the day large plumes of smoke billowed out onto neighbouring streets and onto the quays.

Dublin Fire Brigade said the three shops would all have to be demolished.

One resident living in the building next to Utopia 2, said they heard "a big bang" shortly after 6am and fled their apartment.

"We haven't been told when or if we'll be able to return home and I'm worried because all my belongings are in there," said the resident.

While the cause of the fire is not yet known, Nirvana's owner Jim Bellamy claimed it may have been started deliberately following a widespread campaign against ’head shops’.

Speaking on Newstalk FM he said: “Somebody has taken the law into their own hands by the disgusting media coverage of the last month or so. We have been tried by the media, found guilty . . . and this is the sentence”.

Regulations which will outlaw a range of products sold as “legal highs” in head shops across the State are expected to be introduced later this year.