British prisoner is one of five prisoners on the run after escaping from Portuguese prison

A British prisoner is among five inmates who escaped from a maximum security prison in Portugal.

The search continues for Mark Cameron Roscaleer and four other prisoners after they escaped from Vale de Judeus prison, about 70 kilometers north of the capital Lisbon, on Saturday.

They escaped by climbing the wall with the help of a ladder and having “external help,” the Portuguese prison service told Reuters.

According to Portuguese media, Roscaleer is serving a nine-year prison sentence for kidnapping and robbery.

Vale de Judeus is a maximum security prison with a capacity of 560 inmates, according to its website.

The prison service said the outbreak occurred at 10am local time (09:00 GMT) on Saturday morning.

According to Portuguese media, among the five occupants were Roscaleer, two Portuguese, an Argentinian and a Georgian.

The two Portuguese escapees were serving 25-year prison sentences for crimes including drug trafficking, criminal association, theft, robbery and kidnapping, the Portuguese prison service told Reuters.

The other three were convicted of crimes such as theft, kidnapping and robbery.

“Extremely dangerous”

Portugal's national prison guards' union – the Sindicato Nacional do Corpo da Guarda Prisional (SNCGP) – shared mugshots of the five on social media.

Frederico Morais, head of the SNCGP, told Portuguese news channel SIC Noticias that the prisoners were extremely dangerous and the public should not approach them.

Mr Morais also said the breakout occurred due to a lack of prison guards, meaning surveillance towers were not manned, Portuguese news site Diario de Noticias reported.

The prison service said the men “escaped with assistance from outside by throwing out a ladder which enabled the inmates to climb over the wall and get outside.”

Portuguese police have reportedly asked for international cooperation in arresting the five detainees.

The BBC has contacted the British Foreign Office.