Out of five prisoners who broke out of a Portuguese high-security jail, one is a British national.

Mark Cameron Roscaleer and four other inmates escaped the Vale de Judeus jail on Saturday, some 43 miles (70 km) north of Lisbon's city, and their whereabouts are still being searched.
They used a ladder to scale the wall and "external help" to enable them escape, the Portuguese prison service claimed, as reported by the Reuters news agency.According to Portuguese media, Roscaleer is serving a nine-year prison term for kidnapping and robbery.

On its website, Vale de Judeus states that it is a 560-inmate high-security jail.

The prison service said the escape happened on Saturday morning, at 10:00 local time (09:00 GMT).

As well as Roscaleer, the five inmates included two Portuguese men, an Argentinian and a Georgian, Portuguese media say.

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

The other three had been convicted of offences such as theft, kidnapping and robbery.

Mugshots of the five were posted on social media by the Sindicato Nacional do Corpo da Guarda Prisional (SNCGP), Portugal's national union for prison guards.

The SNCGP chief, Frederico Morais, warned the public not to approach the prisoners because they were very dangerous, according to Portugal's SIC Noticias news program.

Additionally, Mr. Morais claimed that the breakout occurred because the security towers were unmanned due to a shortage of jail guards, as reported by the Portuguese news outlet Diario de Noticias.

The males managed to get away "with outside assistance through the launch of a ladder, which allowed the inmates to scale the wall and access the outside," according to the prison service.

According to reports, Portuguese authorities have requested foreign assistance in order to apprehend the five prisoners.