US weighs in

The US, a key strategic ally of Egypt, has spoken up, saying it is concerned about "mass violations of human rights" and called for "investigations into use of force by security forces against protesters."

The U.S. froze much of its $1.3 billion in annual military aid to Egypt last year, including the helicopter sales, after the army overthrew President Mohammad Morsi, a leader of the now-banned Muslim Brotherhood Islamist movement.

But in June Secretary of State John Kerry voiced strong U.S. support for Egypt's president Sisi and signaled that Washington will continue the flow of military aid to the post-coup government.

Mr. Kerry said that the U.S. had recently released $575 million in assistance for Egypt's military and that he was confident 10 Apache helicopters would be delivered to Egypt soon.