President Barack Obama has vowed a renewed push to close the the prison in Guantanamo Bay amid a growing prison hunger strike there.

At a White House press briefing on Tuesday Obama said the prison at Guantanamo “needs to be closed” and committed to reviewing administrative steps and reengaging with Congress to do so. The president’s remarks came amid reports that more than 100 prisoners at Guantanamo were participating in a hunger strike and that the military is force feeding many of them.

US President Barack Obama should move swiftly to fulfill newly repeated promises to end indefinite detention without trial at the US military prison at Guantanamo Bay, Human Rights Watch said in a statement.

“President Obama’s call to end indefinite detention at Guantanamo is encouraging after his long silence on the issue,” said Laura Pitter, counterterrorism advisor at Human Rights Watch.

“Though he blamed Congress for the problems at Guantanamo, there are actions he could have taken and can still take now to end indefinite detention there.”

When Obama first took office in 2009, he promised to close the prison at Guantanamo Bay within one year. More than four years later, 166 prisoners remain imprisoned, only a handful of whom face charges.

Obama has pointed to congressional restrictions on transfers of prisoners from the Guantanamo Bay prison as an obstacle to closure of the prison, but he himself has repeatedly signed those restrictions into law, Human Rights Watch said. And the restrictions are not a complete bar – instead, they require the Defense Secretary to ensure certain conditions have been met in the transfer countries.

Of the prisoners now at Guantanamo, the Obama administration has in the past designated 86 for transfer to their home or third countries if security conditions could be met.

The media has reported that the military has deployed “medical reinforcements” to the prisons to assist with feedings of at least 21 of the hunger strikers who have refused sustenance. Five prisoners are reportedly hospitalized.