A special Egyptian court on Sunday sentenced four veteran human rights activists to prison terms up to 15 years for "terrorism", several rights groups said.

Mohammed Abu Horayra, a lawyer, received a 15-year sentence, according to the Egyptian Initiative for Personal Rights and other groups.

They said his wife Aisha Khairat al-Shater, the daughter of former Muslim Brotherhood leader Khairat al-Shater, got 10 years in prison.

Khairat al-Shater was arrested in a crackdown on the now-outlawed Brotherhood after the military led by current President Abdel Fattah al-Sisi ousted president Mohamed Morsi in 2013.

The late Morsi's Muslim Brotherhood had won national elections, but he was toppled following mass protests against his one-year rule.

Egypt subsequently branded the Brotherhood a "terrorist organisation".

Hoda Abdelmoneim, also a lawyer, received a five-year prison sentence which cannot be appealed, the rights groups said.

In her 60s, Abdelmoneim had been a member of the state's official National Human Rights Council before being arrested in 2018. She was also a spokesperson for Egypt's Women Revolutionary Coalition -- a group close to the Muslim Brotherhood.

Ezzat Ghoneim, another lawyer, received a 15-year prison term, the groups said.

All four were part of the Egyptian Coordination for Rights and Freedoms, a non-governmental group which suspended its activities in 2018 when Abdelmoneim, Shater and other activists were arrested.

Mary Lawlor, the United Nations special rapporteur on human rights defenders, had on Saturday tweeted that she would closely follow the verdict for the four activists.

She said they had been "arbitrarily detained in 2018, forcibly disappeared, tortured & charged in unfair trial with joining a terrorist group."

Egypt regularly uses accusations of support or financing of "terrorism" to hold activists and opposition figures as long as possible in pre-trial detention.

The two-year time limit on such detention is regularly exceeded, say rights groups who count around 60,000 political prisoners in the country.

Many face brutal conditions in overcrowded cells.

Egypt has long been criticised for its rights record.

In September 2021 Sisi launched a national human rights strategy, after reactivating a presidential pardon committee.

He has also promised to hold a national dialogue to revive the country's crushed political opposition before next year's presidential election.