SAN’A, Yemen (AP) – The two young sons of a Yemeni detainee at Guantanamo died when a grenade they were playing with accidentally detonated inside their home, a human rights lawyer and the detainee’s brother said Thursday.

The two boys were the sons of Guantanamo prisoner No. 1463, Abdelsalam al-Hilah, a businessman who was captured in Cairo in 2002 and sent to Guantanamo on charges of terrorism, said Ahmed Irman of the Hood Organization for Defending Human Rights, an organization that advocates for Guantanamo detainees in Yemen.

The children, Youssef, 11, and Omar, 10, were playing unsupervised with the grenade in a room in the house when it exploded. It is unclear why the grenade was in the house.

The detainee’s brother, Nabil al-Hilah, confirmed the boys were killed.

Irman said the boys had just received a rare phone call from their father two days before their death in which they chatted with their dad about their schoolwork and classes they were attending. Irman said their father was shocked to hear how big the boys had grown.

During the two-hour phone call, Irman said al-Hilah spoke about his frustration with being detained for such a long period of time and expressed pessimism at being released in the near future.

Irman said he also spoke about what he described as a bad conditions in Guantanamo and a lack of change since President Barack Obama took office.

The boys were buried on Wednesday. It is unclear if their father has been notified of their death.

The Obama administration has said that it will close the detention facility on Cuba which became a flashpoint for controversy ever since it was opened under the Bush administration. However, questions have been raised about where to send the remaining detainees, the largest group of which is from Yemen.

AP-ES-04-23-09 1711EDT