An 18-year-old man from London could be jailed in the United Arab Emirates after having sex with a 17-year-old girl.

Marcus Fakana, from Tottenham, was on a family holiday in Dubai when he met the British girl, who is also from London and has since turned 18.

He told the Detained in Dubai group: “We really liked each other but she was secretive with her family because they were strict.

“My parents knew about our relationship but she couldn’t tell hers. She had to meet me without telling them it was to see a boy.”

The pair had hoped to continue their relationship back in London after the girl returned home from her holiday. But Fakana said he was taken into custody without any explanation after police turned up at his family’s hotel.

He was detained for three days, Sky News reported, and was unable to contact his parents.

Detained in Dubai, which campaigns to help people it says have suffered injustice in the UAE, said Fakana was charged because the girl’s mother found their chats and pictures back in the UK.

It is understood the woman subsequently contacted police in Dubai and Fakana was arrested.

Campaigners say the teenager could face up to two decades in prison owing to the country’s strict laws regarding sex outside marriage.

“Dubai has only recently legalised out-of-wedlock sex for tourists but still hosts a strict Islamic legal system,” said Radha Stirling, the chief executive of Detained in Dubai. Sex outside marriage is legal for tourists, but only if both parties are over 18.

“The girl was just a few months younger than Marcus and he didn’t know that at the time,” said Stirling. “Since his arrest, she has turned 18.

“This is not something Dubai should be prosecuting.”

In the UK, their relationship would not be illegal. Fakana’s family has called on the foreign secretary, David Lammy – their local MP – to intervene.

Fakana is no longer being held in a police cell but is unable to leave the country, with his family facing bills of £2,000 for Airbnb accommodation until his case is resolved.

He told Detained in Dubai: “[My family] saved up for this one-off holiday and have now used all of their savings.”