Muslim Brotherhood leads march against military

Supporters of Mohamed Morsi, the Muslim Brotherhood candidate, celebrate in Tahrir Square (EPA)

An emboldened Muslim Brotherhood appeared to be on a collision course with Egypt's ruling generals last night, as it called on its millions of supporters to protest against this week's military power grab and the recent dissolution of the Islamist-led parliament.

The call, which followed the Brotherhood's disputed claims of victory in the final round of presidential elections, came as Egypt's unelected army rulers faced further pressure from Washington yesterday. Responding to what commentators have called a "soft coup" – which saw the military carve up substantial new powers for itself via an executive decree – officials in the US said they would review more than a billion dollars in annual military subsidies unless there was a swift handover to civilian rule.

The comments reflect the manner in which Washington's alliance with Cairo – for years a keystone of America's Middle East diplomacy – has grown frosty over the past 18 months. The Obama administration, though nervous about the ascendancy of political Islam, has also grown wary of the authoritarian methods being deployed by Egypt's generals.

In a further development, campaign officials for Ahmed Shafik, the last prime minister to serve under the deposed President Hosni Mubarak, yesterday claimed their man had won the presidential poll. Mohamed Morsi, the Brotherhood candidate, has also claimed victory. Official results are due to be released tomorrow.

Last night further conflict appeared to loom on the horizon, as plans for a "million-man march" in Cairo's Tahrir Square emerged. The demonstration was called by the Muslim Brotherhood, but was also supported by other secular revolutionary groups such as the April 6 youth movement, which played a major role in last year's uprisings.

The move appears to show how the political sands are shifting again in Egypt's mercurial revolution. Liberal political factions have previously accused the Brotherhood of stitching up a closed-door deal with the military in exchange for political gains, and many still subscribe to this view.

But Tamir Fouad, a spokesperson for April 6, said he believed that the Brotherhood is now under no illusions about the military's alleged intentions.