An Egyptian coalition of rights groups said Tuesday that police arrested at least 237 people during the previous day's protests in Cairo against a government decision to hand over to Saudi Arabia control of two strategic Red Sea islands.
Amnesty International condemned the arrests, the latest criticism levelled by the leading international advocacy group over human rights abuses in Egypt.
Rights lawyers Gamal Eid and Mohammed Abdel-Aziz -- both members of the Front for the Defense of Egyptian Protesters -- said that all those detained were in custody by midnight Monday when the front made its last tally.
The number of those still held could be lower since police have been intermittently releasing the detainees, they said. It's unclear if anyone has been referred to prosecutors.
Thousands of police were deployed across much of Cairo on Monday to stifle plans for mass demonstrations called to protest the government's decision to surrender the islands of Tiran and Sanafir.
Faced with the police's overwhelming numbers, protesters resorted to staging flash demonstrations in Cairo, drawing tear gas and birdshot from the riot police.
The arrest of 237 people, mostly in Cairo but also some in the Egyptian capital's twin city of Giza, followed the detention of nearly 100 in pre-dawn house raids and roundups at cafes in downtown Cairo, a popular hangout for young, pro-democracy activists. Those arrests mainly targeted rights activists and journalists.
Amnesty criticized the arrests and the use of violence against protesters in a statement Tuesday.
"The Egyptian authorities appear to have orchestrated a heavy-handed and ruthlessly efficient campaign to squash this protest before it even began," said Magdalena Mughrabi of the group's Middle East and North Africa section. "Mass arrests, road blocks and huge deployments of security forces made it impossible for peaceful demonstrations to take place."
Authorities say the objective of the large deployment of police was to protect vital installations and Egyptians celebrating a holiday marking the final Israeli pullout from the Sinai Peninsula in 1982.
Egypt says the islands of Tiran and Sanafir at the mouth of the Gulf of Aqaba off the southern coast of Sinai belong to Saudi Arabia, which placed them under Cairo's protection in 1950 because it feared Israel might attack them. The announcement that they would be returned to the Saudis was made during a visit to Egypt this month by Saudi Arabia's King Salman as the kingdom announced a multi-billion-dollar aid package to Egypt. The timing fueled charges that the islands were sold off.
Already, the issue of the islands has sparked the largest protests since el-Sissi assumed power in June 2014, when on April 15 some 2,000 protesters gathered in downtown Cairo to shout slogans against el-Sissi for giving up the islands, calling on him to step down. El-Sissi has dismissed the controversy and insists Egypt has not surrendered an "inch" of its territory.