The boys, aged six and eight, and a 44-year-old British man, were taken to hospital suffering “grievous injuries” said police in Malta.

Officers were called to the scene of the crash at around 4.15pm on Monday (April 9) in Valletta Road, Zurrieq.

A 37-year-old Spanish woman and a 62-year-old Belgian man were killed.

Three other people, a 31-year-old German woman, a 72-year-old Italian woman and a 35-year-old man whose nationality is yet to be established, were also hurt.

All six have been taken to Mater Dei Hospital for treatment.

Police said the double-decker bus struck a tree branch and that an investigation was under way.

City Sightseeing, the company behind the bus tours, said in a statement issued on Facebook: “We are shocked and saddened to learn a vehicle operated by our Maltese franchise holder has been involved in a serious accident.

“Our thoughts and prayers are with all of those affected by this tragic event. We are communicating with our franchise operator with a view to establish the full facts of the situation, and are not in a position to comment further at this time.”

A Foreign Office spokesperson said: "We are supporting British people and their families involved in the bus incident in Malta."