Spanish national Saif Abu Keshek and Brazilian Thiago Avila, who are held in a prison in Ashkelon, were among dozens of activists on a Gaza-bound flotilla intercepted by Israeli forces in international waters off the coast of Greece last Thursday.

“Israel must immediately and unconditionally release Global Sumud Flotilla members Saif Abu Keshek and Thiago Avila, who were detained in international waters and brought to Israel, where they continue to be held without charge,” UN rights office spokesman Thameen Al-Kheetan said in a statement.

“It is not a crime to show solidarity and attempt to bring humanitarian aid to the Palestinian population in Gaza, who are in dire need of it,” he insisted.

The flotilla’s vessels set sail from France, Spain and Italy with the aim of breaking Israel’s blockade of Gaza and delivering humanitarian aid to the war-ravaged Palestinian territory.

Representatives for Avila and Abu Keshek have accused Israeli authorities of abusing the two men, who have been on hunger strike for the past six days.

Kheetan decried the “disturbing accounts of severe mistreatment”, calling for an investigation and insisting “those responsible must be brought to justice”.

“We call for an end to Israel’s use of arbitrary detention and of broadly and vaguely defined terrorism legislation, inconsistent with international human rights law,” he said.

“Israel must also end its blockade on Gaza and allow and facilitate the entry of humanitarian assistance to the besieged Palestinian strip in sufficient amounts,” the spokesman said.