Gamal Mubarak, son of former Egyptian President Hosni Mubarak, reacts inside a cage in a courtroom at the police academy in Cairo May 21, 2014.

CAIRO — An Egyptian court ordered the release of the sons of ousted president Hosni Mubarak on Thursday pending a retrial, their lawyer said, as rare protests erupted days before the anniversary of the 2011 uprising that toppled the autocrat.

Lawyer Farid el-Deeb said the order for the release of Alaa and Gamal Mubarak should mean they immediaately walk free.

The Cairo Criminal Court said in a document explaining its ruling that the two men had already served the maximum permitted time of 18 months in pretrial detention and should therefore not be held pending their retrial in a corruption case.

The retrial was ordered by Egypt’s high court earlier this month. A court had already dropped other graft charges against the sons in November.

Egypt has witnessed rare street anti-government protests before the anniversary of the popular revolt that ended three decades of iron-fisted rule under Mubarak and raised hopes of greater freedom and accountability.

Tensions have been rising for the first time in months.

On Thursday, security forces quickly dispersed protesters in downtown Cairo after a similar incident on Wednesday night in the same area.

Muslim Brotherhood supporters blocked traffic in Egypt’s second city of Alexandria on Thursday and hurled Molotov cocktails, security sources said. Thirteen people were arrested.

The army, led at the time by Abdel Fattah al-Sisi, removed the Brotherhood from power in 2013 after mass protests against their rule. It has since mounted a tough crackdown on the Islamist movement.

In November, a court dropped charges against Mubarak of conspiring to kill protesters in the 2011 uprising, raising fears among human rights activists that the old guard was making a comeback.