Egyptian police have arrested Muslim Brotherhood spokesman Gehad al-Haddad after being found with two other Brotherhood officials in a flat in Cairo, according to BBC News.

Haddad had served as chief of staff of the Brotherhood's deputy general guide, Khairat al-Shater, and often spoke to English-language media.

There has been a crackdown on Islamist groups since the military ousted President Mohammed Morsi in July.

Earlier, the Cairo Criminal Court upheld an order to freeze the assets of senior figures in the Brotherhood and the former militant group Gamaa Islamiya, state media said.

Prosecutors imposed the restrictions on the Brotherhood's general guide, Mohammed Badie, Shater and about a dozen others in July.

Most of those affected have since been detained over allegations of inciting violence and murder.

Hundreds of people demanding Morsi's reinstatement, most of them Brotherhood members, have also been killed in clashes with security forces.