A British schoolboy who has been in the custody of his father’s family in Qatar for nearly three years has appealed to David Cameron to help reunite him with his mother.

Cameron has written to his Qatari counterpart, Shaikh Hamad Bin Jasem Bin Jabr Al Thani, and Qatar’s Emir Shaikh Hamad Bin Khalifa Al Thani to demand that “Adam’s voice is heard” and that the case is “speedily resolved”.

In a recent letter to Adam, Cameron pledged that he would personally keep urging the Qatari royal family to ensure that Adam’s wish to return to his mother be granted. Cameron states: “I was very sorry to read that you are still separated from your mum. This must be very hard for you, but I want you to know that you are still in my thoughts. I will keep trying as hard as I can to help you, and I hope your family situation will change for the better very soon.”

In a handwritten addendum, Cameron states: “I promise I have not forgotten about you and will keep trying to make some progress.”

His letter followed a plea from Adam, who 11 months earlier had turned to him in desperation. On April 25 this year, Adam wrote again: “It is nearly one year since I wrote to you asking for your help. I was so happy when you wrote back and told me you would do your best to help me get home. Did you forget about me? I want to go home now and I’m very sad and lonely.”

Adam reveals that he has also asked for Prince Charles’ intervention because “nothing has happened and I think no one cares about me”.

The alleged abduction of Adam is a continuing focus of diplomacy between Britain and Qatar, his case having being raised personally by the Queen Elizabeth II during a meeting with Shaikh Hamad. The Foreign Office’s child abduction section is also involved, with a spokesman saying it recognised the “enormous distress faced by Rebecca Jones in being separated from her son and we sincerely hope she is reunited with him soon”.

Yet the Qatari Prime Minister’s written response to Cameron states only that he will try “to find an amicable solution that preserves the rights of all parties involved”.

Rebecca Jones said her son was effectively a prisoner at the high-walled, gated home of his Qatari relatives and was forbidden to visit friends. Even at school, the 45-year-old from Sheffield claimed, Adam was escorted between classrooms and held in a room after lessons to be picked up by relatives.

She said the ordeal began after she and Adam were invited to visit the parents of her late ex-husband on October 3, 2009. Rebecca was separated from Adam’s Qatari father Jamal, who died in a motorbike accident in 2005, but stayed in contact with his family to allow them access to Adam.

On the morning they were due to return to Bahrain, where Rebecca had taken a teaching job, she said she received a call asking if Adam could visit his sick grandmother. She agreed and a driver picked up Adam. Shortly afterwards, his uncle, Fahd Al Mudhaki, rang and asked to meet her to discuss dividing up the proceeds of land belonging to Adam’s father. Although the documents were in Arabic, Rebecca says she trusted Al Mudhaki’s explanation that they comprised paperwork designed to safeguard Adam’s inheritance and signed them. “I just wanted to go home with my son and was not interested in the lands or money my son had been left by his father. It did not occur to me what would happen.”

The documents were to be used to kickstart the Al Mudhakis’ custody claim against Rebecca. Within minutes of signing, Rebecca says she realised she had been duped. She alleges that her husband’s relatives told her that she had been deliberately deceived: “I’ll never forget what Adam’s uncle Fahd told me: ‘I have lied to you and tricked you, Jamal did not take your son but I will’.”

The Al Mudhakis had obtained a court order in 2008 to win custody of Adam, confirming to Rebecca the abduction was premeditated. A custody hearing was already arranged for October 13, days after the alleged kidnapping. “I felt sick to the stomach to realise that I had fallen easily into their trap.”

Adam, then 10, has been separated from his mother ever since, despite a series of custody appeals and Rebecca’s offer to waive Adam’s inheritance. A subsequent hearing ruled that Rebecca, who also has a four-year-old daughter Alex, is allowed to visit Adam twice weekly, but never unsupervised.

She says the teenager is increasingly depressed. Since being taken, Adam has seen his sister twice, while the Al Mudhakis refuse to let Adam’s British grandmother, 74, visit him.

“For the last three years Alex won’t sleep in her own bed,” said Rebecca, “she’s scared somebody is going to take her.”

Fahd Al Mudhaki is a senior police officer, a fact which Rebecca believes he has used against her. During her first visit to see Adam, eight weeks after he was taken, she said that 15 armed police officers surrounded the Al Mudhaki house and Rebecca was flanked by officers throughout their meeting. She says she has suffered a constant campaign of intimidation, sometimes receiving up to 20 calls a day from police, and each time she enters Qatar to visit Adam is terrified that she might be arrested.

A document from the British embassy in Doha states: “the child was kidnapped by his uncle Mr Fahd Juma Abdullah Al Mudhaki, a Qatari police officer.”

Rebecca said: “I’ve been terrorised and treated as a criminal. We are still suffering every day without our little boy. The pain has not gotten easier as time has passed because I cannot accept what has happened.”