Egyptian authorities have detained prominent opposition leader Hazim Abdelazim, three security sources told Reuters on Sunday, the latest development in what rights groups say is a campaign to silence government critics.

Egypt has in recent weeks arrested several prominent activists in a crackdown on critics that followed small protests against hikes in metro fares.

Abdelazim was arrested at his home in Cairo late on Saturday night on suspicion of publishing false news and inciting against the state, one source said.

Once a deputy telecoms minister under ousted President Hosni Mubarak, Abdelazim was later heavily involved with Egyptian President Abdel Fattah al-Sisi’s 2014 election campaign where he chaired the youth committee.

He later described the experience on his Twitter profile as his “biggest sin.”

The interior ministry could not immediately be reached for comment.

Last week, Egyptian authorities arrested award-winning blogger and journalist Wael Abbas, accusing him of involvement with an illegal organization and publishing false news.

Abbas’s arrest followed those of at least three other prominent opposition figures.

Rights groups say Egypt’s human and civil rights record has deteriorated under Sisi, but his supporters say his tough security policy is needed to ensure stability as Egypt recovers from years of political chaos and tackles economic challenges and an Islamist insurgency.

Sisi won a second term in office in a March election that featured only one other candidate – himself an ardent Sisi supporter – after all serious opposition contenders halted their campaigns citing intimidation and several arrests.