Ramallah, occupied West Bank - Thousands of Palestinians took to the streets across the West Bank and Gaza Strip on Sunday to mark Prisoners Day, to shed light on the plight of 7,000 compatriots who are incarcerated by Israel.

Prisoners Day has been commemorated annually since 1974, after the first Palestinian detainee - Mahmoud Hijazi - was released in a swap deal with Israel.

In the centre of the West Bank city of Ramallah, families gathered raising Palestinian flags and holding framed pictures and posters of their incarcerated loved ones: Faheem al-Khateeb, who has been in prison since 2015, Adeeb Mafarjeh, currently on hunger strike, and Marwan al-Barghouti, the Fatah leader and parliamentarian, who some refer to as the "Palestinian Mandela".

"There are 750 administrative detainees, three of them women, and there are 700 sick prisoners," said Issa Qaraqe, head of the Palestine Liberation Organisation Commission for Prisoners Affairs. Administrative detainees can be held without trial or charge for extended periods of time.

"We will spare no effort to have them released by either turning to international bodies, like the International Criminal Court, or by continuing to shed light on their plight with events like these," Qaraqe added.

READ MORE: Palestinian hunger strikes - 'My husband is dying'

A tearful mother, who was carrying a picture of her son, said she is no longer allowed to visit him in prison.

"My visitation rights were taken away, because Israeli authorities claimed I was carrying a knife," said the mother of Eyad Fawaghreh, who has been on hunger strike for more than a month to protest against the denial of family visits.

Fawaghreh, who has served 11 of a 27-year sentence, is refusing painkillers and vitamins until his visitation rights are restored, said Yousef al-Nasassra, a lawyer representing him.

There are 30 prisoners who have been incarcerated since before the Oslo Peace Accords were signed in 1993 between the PLO and Israel, according to the Palestinian Prisoners Club. Among the prisoners are six members of parliament and 18 journalists, the group said.

In Jenin, high schools on Sunday dedicated one class to teaching about the prisoner population, which includes 75 students and 30 teachers, according to the PA Ministry of Education.

Local radio stations aired stories about incarcerated Palestinians, churches tolled their bells, and mosques used their loudspeakers to pray for prisoners throughout the day.

Outside the premises of the Red Cross, some gathered to sign a petition calling for the release of their loved ones.

"We call upon the international community to investigate the violations against our brothers and sisters inside Israeli prisons," said Mansour al-Saadi, Jenin's deputy governor.

"Israel is even imprisoning 12-year-olds. Where is the outrage?" he asked, referring to a Palestinian child currently being held by Israel and due to be released on April 24.

READ MORE: Youngest prisoner in Israeli jail is a 12-year-old girl

In Gaza City, members of the various political factions - including warring parties Hamas and Fatah - took part in a rally that ended outside the Red Cross premises.

As party members used the occasion to highlight the need for ending the division between the two factions, the group slammed the PA, and its ruling party Fatah, which it said was doing an "inadequate job supporting the prisoners".

"The prisoners' case must be brought to the negotiating table," said Wasfi Qabha, a Hamas leader, and former minister of detainees. "The PA signed a peace agreement with Israel without securing any guarantees to release our prisoners."