Gaza, June 28 : Hamas, the militant organisation ruling the Gaza Strip, said the health condition of an Israeli captive in the besieged enclave has deteriorated. Taking to Twitter, Abu Obeida, the spokesman of Al-Qassam Brigades, Hamas' armed wing, only said that the health of one of their Israeli hostages has deteriorated, without providing any further details. He however, said that evidence would be published in the coming hours. On Monday night, the Israeli Prime Minister's office blamed Hamas for the state of the captured civilians, saying the Jewish state will "continue its efforts, mediated by Egypt, to bring home the captives and the missing, with responsibility and determination". An Israeli security official told local media that Hamas' announcement "appears to be an attempt to pressure Israel within the framework of negotiations for a prisoner swap deal". Israel believes that Hamas holds the remains of Oron Shaul and Hadar Goldin, two soldiers that were killed in Gaza during the country's military offensive in 2014, as well as two civilians who are believed to be alive, Avera Mengistu and Hisham al-Sayed. In 2016, Al-Qassam Brigades announced for the first time that it keeps four Israeli soldiers in its captivity, without specifying their fate. Hamas has sought to trade the prisoners in exchange for relief in the blockade on Gaza that Israel has imposed since 2007. Israel maintains it will not lift the blockade until the prisoners are freed and the Gaza Strip is demilitarized. /IANS