Ministers were urged by Labour to press President Obama to halt the US supply of arms to Egypt because of the “horrific bloodshed” as Britain called for a UN Security Council meeting over the crisis.
Britain, France and Australia issued a joint statement calling for a closed session of the UN Security Council, the Foreign Office said. But Douglas Alexander, the shadow Foreign Secretary, also called for Europe to review all the aid it gives to the Egyptian government.
The US sends military hardware worth about $1.3bn (£830m) to Egypt every year. Today Mr Obama announced the cancellation of a joint military exercise between the two nations, but made no reference to the continuing supply of weapons.
Mr Alexander said: "It was right for the United States to try, through quiet diplomacy, to influence the Egyptian military authorities towards a democratic path.… [But] the time has now come for the UK government to urge the US administration to suspend its $1.3bn military aid to Egypt."
Last month Vince Cable, the Business Secretary, cancelled the export licences of five British companies selling military equipment to Egypt.
Egypt's ambassador to the UK, Ashraf El-Kholy, defended Wednesday's crackdown by security forces. Speaking in London he said that the police and army were fired upon first by demonstrators.