A former jihadist group says it will back a moderate Islamist candidate for Egypt's president, dealing a blow to the powerful Muslim Brotherhood.

Assem Abdel-Maged of the Gamaa Islamiya said on Monday that an internal poll showed that a majority in the group supported moderate Islamist Abdel-Moneim Abolfotoh.

The decision boosts Abolfotoh's chances in the Gamaa's strongholds in southern Egypt and leaves the Muslim Brotherhood, Egypt's largest political group, more isolated as it moves closer to a confrontation with Egypt's ruling generals.

In a surprise decision, an influential group of ultraconservative Salafis said last week it was supporting Abolfotoh for the May 23-24 vote.

The Brotherhood won just under half the seats in parliament in recent elections.