A court on Wednesday sentenced one of Egypt's best-known activists, Ahmed Douma, to 15 years' jail for rioting and attacking security forces in 2011, judicial sources said.
The ruling is part of what rights groups term the worst crackdown on activists since the military ousted Islamist President Mohamed Mursi five years ago.
Thousands of Islamist opponents, plus scores of liberal activists and journalists, have been jailed since his toppling.
Douma, a leading figure in the pro-democracy revolt that toppled autocrat Hosni Mubarak in 2011, had previously been sentenced to three years' jail over separate charges of taking part in a 2013 demonstration in downtown Cairo.
The Cairo court on Wednesday also ordered Douma to pay six million Egyptian pounds ($336,0005) for damages he was accused of during the protest outside the prime minister's office in 2011. The sentence is subject to appeal within 60 days.
In delivering his verdict, the judge said Douma was part of a crowd that broke into parliament and damaged part of it, describing them as doing the work of the "devil", according to a text received by Reuters.
Like several other prominent activists in Egypt, Douma has been jailed under Mubarak, the subsequent ruling military council, Mursi and current President Abdel Fattah al-Sisi.