Four members of a family with British passports have died after a head-on crash in a hire car they had just rented at Faro Airport, Portugal.

The victims include 20-year-old twins, their 55-year-old father and their 51-year-old mum. The 19-year-old girlfriend of one of the siblings also died in the horror accident, which claimed the life of a Portuguese man travelling alone in the other car they collided with.

It's believed the group was travelling north from the Algarve towards Mourao in the district of Evora, which is near the Spanish border, at around 1.40am this morning when tragedy struck on the IP2 main road in Castro Verde around halfway to their final destination.

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Well-placed police sources said all four members of the same family killed were British passport holders, although the twins’ parents hailed from Mourao and were returning to the municipality for holidays.

They added that the twins were both born in the UK, despite Mourao Town Hall describing all four as coming from the municipality but living in Britain. The girlfriend of one of the boys is believed to be of Polish origin but also lived in the UK.

It's unknown yet where the family lived in Britain or when they emigrated from the UK, but the man travelling alone in the other car has been named locally as Ruben Goncalves.

Mr Gonclaves is understood to have come from a town in Portugal called Almodovar. He was travelling south on the IP2.

The circumstances surrounding the fatal accident were today being investigated by the GNR local police force, it has been confirmed. Town hall officials in Mourao have declared two days of mourning starting from tomorrow.

A spokesman said: “The Municipal Council of Mourao has decreed two days of municipal mourning, effective from tomorrow, Sunday, following the death of five family members involved in a traffic accident last night on the IP2, near Castro Verde.

“The Municipality, in coordination with the family and law enforcement authorities, namely the local GNR Post in Castro Verde, obtained the number plate of the vehicle they were travelling in and confirmed the identity of the passengers at 3:35 p.m today.

“There were four occupants in the car, all from Mourao, and a young woman with ties to the family. Residents of England, they were traveling from Faro to Mourao for their usual and well-deserved vacation.

“It is with great sadness that the Municipality announces this information, offering its condolences to the families and friends of the victims.

“We inform you that all activities and events promoted by the Municipality are cancelled for the entire weekend.”