“All Brothers have to realise that we cannot support an oppressor or cooperate with a corrupt person or a dictator,” said a much-anticipated official statement stating the powerful movement’s voting advice.

President Hosni Mubarak, who has ruled Egypt for 24 years, is seeking a fifth term in office but has for the first time allowed others to challenge him for the job.

“It is unthinkable for us to decide to back Mubarak,” the movement’s supreme leader, Mohammed Mahdi Akef, told the Al-Hayat daily on Saturday.

“The fact that he has ruled over Egypt for 24 years and has not introduced a single political reform over that period is enough justification,” he added.

The brotherhood is not fielding a candidate in the election as it has officially been banned since 1954, with the Egyptian government allowing it to operate whilst sporadically turning up the heat on its activists.

The Islamist movement, which claims an active membership of two million and the support of another three million nationwide, has been courted by several parties to throw its weight behind one of the 10 presidential candidates.

A week ago, secular Ghad party leader Ayman Nur one of the Mubarak’s main challengers  joined Akef in a prayer session at the Muslim Brotherhood’s headquarters to seek the movement’s endorsement.