CAIRO (AP) — An Egyptian rights lawyer says prosecutors have ordered the brother of a U.S.-based well-known Egyptian activist to remain in custody pending an investigation into taking part in activities of an outlawed group and disseminating fake news.

Wael Ghonim, who led a Facebook page that helped ignite the 2011 pro-democracy uprising, has said security forces arrested his brother Hazem Thursday.

Lawyer Mohammed el-Baker tells The Associated Press Sunday that prosecutors ordered Hazim Ghonim to remain in custody for 15 days.

Wael Ghonim claimed that his recent criticism of President Abdel-Fattah el-Sissi prompted authorities to retaliate by detaining his brother.

The arrest came as Egyptian social media was awash with calls for anti-government protests last week. On Friday, hundreds joined in scattered, small protests in Cairo and other cities.