Israel appealed to Pope Francis, the head of the International Committee of the Red Cross and the United Nations Secretary-General on Wednesday to help it recover four citizens held in the Gaza Strip for more than seven years. 

Foreign Minister Eli Cohen's office said he sent letters of appeal after Gaza's ruling Palestinian Islamist group Hamas released a video of captive Avera Mengistu, who walked into the enclave and whose family says he suffers from mental illness.

Another Israeli civilian is being held in Gaza after entering under similar circumstances in 2015, as are two Israeli soldiers who went missing during a war with Hamas in 2014 and were declared dead by the army. 

In his letters, Cohen described Mengistu's plight as "a gross violation of international humanitarian law, with no information on his health condition nor means of communication with family nor Red Cross visits," the Foreign Ministry said.

The release of the video on Monday appeared to be an effort by Hamas to pressure Israel into a prisoner swap. Israel has said it was exploring indirect talks with Hamas on recovering the four, without specifying what it might give in return.