Up to 40 people have been injured in a large explosion in a building next to the office of the International Air Transport Association (Iata) in central Prague.

In a statement Iata said two of their employees were in the building at the time but were uninjured. Their office has been closed until further notice.

Police have sealed off an area around the blast site in Divadelni Street and neighbouring buildings have been evacuated.

Officers investigating the explosion say the most likely cause was an accidental gas leak.

It is understood about 15 people were inside the building, which is also an art gallery, at the time. Prague’s mayor told Czech radio three of them may be trapped in the rubble.

The site is close to the Vltava river, and near the country’s National Theatre.

A Foreign Office spokesman said no British people were thought to have been involved.

A spokesman for Iata said: “At around 10am this morning an explosion occured in the building next to Iata’s Prague office.

“Inital reports are that this was an accidental gas explosion which blew out the windows of several surrounding buildings including the building housing the Iata office.

“Two Iata employees were in the building, but fortunately neither was hurt.

“The building has been closed until further notice by the police. In the meantime, the Iata business continuity plan has been implemented. Airline financial settlement is handled through Iata’s Madrid office, so there will be no disruption to services.

“Other activities of the office will be relocated as per the continuity plan.

“Iata extends its sympathy to all injured in this incident, and expresses its thanks to the emergency services for their efficient and effective response.”