Around 400 relatives of 84 Islamist prisoners in Jordan demonstrated in Amman on Tuesday to demand their release as 27 of the inmates launched a hunger strike.

"If the country respected itself and had justice, a probe into the violation of the prisoners' human rights would have been opened," Saad Hneiti, a sharia (Islamic law) professor, told the protesters outside Al-Husseini mosque in the city centre.

"We will not remain silent about injustice. We will maintain our demands," he said as the demonstrators carried banners reading "time to free our children."

Police spokesman Mohammad Khatib said 27 Islamist inmates "began a hunger strike today without say why," at the Swaqa prison south of Amman.

"They have the right to do so but we will continue to provide them with food, water and medical care," he told AFP.

In May, 61 inmates went on a hunger strike for several days to demand improved conditions.

International and local human rights organisations as well as the opposition, including the Islamist movement, have demanded that the government reform Jordan's prisons, ban torture and protect prisoners' rights.

Meanwhile, more than 100 people demonstrated outside the prime minister's office to demand the release a Jordanian soldier serving a life sentence for killing Israeli schoolgirls in 1997.

Ahmad Dakamseh's attack came less than three years after Jordan and Israel signed their peace treaty, and his motives were never clear.