The family of Osama bin Laden's youngest wife has petitioned the chief justice of Pakistan to order her release and that of her children from the Pakistani authorities.

Zakaria Ahmad al-Sadah, the brother of Bin Laden's Yemeni wife, Amal Ahmed al-Sadah, appealed directly to the chief justice, Iftikhar Chaudhry. He said in an interview with The Guardian that the petition was a "last resort" after he spent over three fruitless months in Pakistan and was repeatedly promised by officials that Amal would be let go.

Sadah said his sister's five children were in poor mental health and were receiving no education. He added that Amal still could not walk as her leg wound was not treated properly. She was shot in the knee after apparently trying to shield Bin Laden during the US raid on their Abbottabad hideout on 2 May last year. The Bin Laden family members found at the Abbottabad house have been in Pakistani custody, at a secret location, since then.

"I put between your hand the issue of Osama bin Laden's family (children and women) who passed upon their illegal disappearance in Pakistan more than eight months with Pakistani authorities despite they are innocent, and which consider against all the human rights and justice laws in the world," says the appeal, written in broken English.

"This enforced disappearance deteriorated the children health and their psychological trauma due to their Abbottabad event."

Sadah lodged the two-page petition with the supreme court on 9 February. A 24-year-old student at the University of Sana'a, he has been allowed to meet with his sister and the children some 10 times since he arrived in Pakistan on 1 November. Along with four grandchildren of Bin Laden and two other wives, they are being kept under de facto house arrest in a small apartment in Islamabad by security personnel. Sadah declined to disclose its location.

He said the children were so traumatised that "I had to teach them how to smile".

Amal, 31, from Yemen, married Bin Laden in 2000 and had five children with him. The oldest, Safia, aged around 12, was reportedly cradling her injured mother when Pakistani officials reached the compound in Abbottabad on 2 May, just after US forces had left with Bin Laden's body. Amal's other children are Ibrahim, Asia, Zainab, and Hussain. Sadah said he believed they were beteween the ages of three and eight. The two youngest are thought to have been born in the Abbottabad house.

"These are innocent children, totally innocent," said Sadah. "Their psychological problems are getting worse and worse."

Two other wives of Bin Laden, both Saudis, who also lived in Abbottabad with him, are also being held, along with four of his grandchildren.

Pakistan's official commission formed to investigate Bin Laden's presence in the country interviewed his wives and called in October last year for them to be sent back to their home countries. Sadah said that he travelled to Pakistan on 1 November only after being assured by the Pakistani authorities that he would be able to take Amal home the next day. For the last month, he has been stopped from seeing his sister and her children.

"I went to the supreme court because I know that Iftikhar Chaudhry is a very just person. I had heard about him even in Yemen," said Sadah. "I have a lot of trust in Iftikhar Chaudhry."

Sadah said the repatriation only awaited the signature of the interior minister, Rehman Malik. However, it is likely that the Bin Laden family are not being held by civilian authorities but are in the custody of the military's main spy agency, Inter-Services Intelligence (ISI). That would mean that the decision is in not in the hands of the interior minister, who did not return calls.

Chaudhry, known for his efforts to hold the government to account, including over human rights issues, has also at times taken up cases against the military. This week he forced the ISI to produce in court seven men that had vanished, apparently into the custody of the spy agency, four years earlier.

There is no evidence that any of the wives of Bin Laden, who married six times and fathered at least 21 children, were involved in al-Qaida. Sadah said his sister was a "housewife" who only spent her married life raising their children.