Egyptian authorities imposed travel restrictions on Syrians in July, requiring them to obtain a visa and a security clearance prior to their arrival. Heated media campaigns also claim Syrian refugees participate in the protests calling for Morsi's reinstatement.
Egypt's interim authorities repeatedly have denied discriminating against Syrians, while right groups say Egypt unlawfully detains and deports them.
An official from the United Nations Refugee Agency in Egypt, Mohamed Dayri, said authorities currently detain 128 Syrian refugees in Egypt who tried to travel illegally to Europe through the Mediterranean Sea. Dayri said they usually are held until they buy a ticket to leave Egypt.
He said the strike appeared to be prompted by recent comments made by Sweden announcing they would resettle a limited number of Syrian refugees there.
"We have called upon Egyptian authorities to release them because they have been acquitted by prosecutors from any legal charges," Dayri said.
Syria's civil war started as a peaceful uprising against President Bashar Assad that deteriorated into all-out civil war after a government forces violently cracked down on protesters. The United Nations said in July that 100,000 Syrians have been killed, while activists say more than 120,000 have been killed. Millions of Syrians have been uprooted from their homes because of the fighting, seeking refuge in neighboring countries.
The website of the U.N. Refugee Agency quotes Egyptian government figures saying there are some 300,000 Syrians in Egypt. The UNHCR has registered more than 127,000.