Exclusive by Adam Williams

A Kent University lecturer is continuing to fight for access to his estranged Brazilian daughter, even after spending 15 days inside a Sao Paulo prison.

Martin Boyle pictured right and originally from Sunderland, hit the national headlines last year when police detained him at the airport, before locking him up in a 3m by 4m cell, with up to 20 other inmates.

The crime was alleged unpaid child maintenance for his 17-year-old daughter, Rebeca, who the 42-year-old has not seen since her third birthday.

Mr Boyle, of Tower Parade, Whitstable was eventually released after his father and lawyer arranged for the outstanding payments to be sent to the British Consulate.

The English Language tutor has been told in no uncertain terms not to return to Brazil to trace Rebeca.

To raise awareness of the situation, he has now launched an online petition calling on the UK Government to put pressure on Brazil, which he claims is failing to adhere to a convention on basic human rights.

It needs at least 1,000 people to sign it by October 1, and can be found here.

Mr Boyle said: "Finding my daughter occupies my whole life.

"I wake up thinking about it and when I go to sleep, it's the last thing on my mind."

Martin estimates to have spent as much as £50,000 on his bid to trace Rebeca, setting up campaign pages in both Britain and Brazil on social networking sites like Facebook.

He claims his daughter has been fraudulently adopted and had her name changed by the family of his former partner, Mara, 44, who he met in 1987, while she was studying in London.

He has no intention of taking Rebeca back to Britain or taking her away from her family, he just wants to be able to see a daughter he last spoke to on the phone in 2002.

He has pursued the case through numerous channels, including Kent Police, Missing Persons, The Foreign and Commonwealth Office and even Interpol. However, his strongest argument to gain access vanished after his trip to Brazil last year.

Under the Hague Convention, both Britain and Brazil are signatories to acting on cases of international child abduction.

In cases like Martin's, both countries have a duty to ensure the safe return of missing children and so-called left-behind parents. But now Rebeca has turned 17, she is no longer classed as a child and Martin's case to gain access under the Hague Convention has fallen through.

He added: "The family knew all along that if they could keep stalling the authorities again and again until her 17th birthday, my case would fall flat.

"Brazil is currently being investigated for numerous cases of non-compliance with the convention and my case is most likely just the latest in a long line of breaches."

Click here to sign the petition.