Egypt's official MENA news agency says authorities have issued an arrest warrant for a key Islamist politician and requested that another's immunity be lifted, so that both can be questioned over allegations they insulted the judiciary.

The case of the two politicians is part of a long struggle between the judiciary and Islamists, who claim that Egypt's courts are filled with loyalists of ousted leader Hosni Mubarak trying to derail Egypt's shift to democratic rule.

MENA said judges on Tuesday ordered the arrest of Essam Sultan of the Islamist Wasat party for questioning over insulting the judiciary in media interviews. They also asked the Justice Minister to cancel the immunity of lawmaker Sobhi Saleh of the Muslim Brotherhood, the powerful Islamist group from which President Mohammed Morsi hails.