A senior US senator has moved to block hundreds of millions of dollars in aid to Egypt to protest the death sentences imposed on nearly 700 suspected Islamists. Denouncing Egypt's "dictatorship run amok" and its "egregious violation of human rights," Democrat Patrick Leahy, who heads the subcommittee overseeing foreign aid appropriations, said he will put a hold on the $650 million in military aid greenlighted by the Pentagon last week. "I am not prepared to sign off on the delivery of additional aid for the Egyptian military," Leahy said in a floor speech Tuesday. "I am not prepared to do that until we see convincing evidence the government is committed to the rule of law." The US administration last week partially lifted a six-month freeze on some $1.5 billion in mostly military aid to Cairo -- a key regional ally. Washington had agreed to deliver 10 Apache helicopters for counterterrorism efforts in the unruly Sinai peninsula and some $650 million in military aid, but withheld the rest of the funding until democratic progress is made. But Leahy said Egypt is not worthy of the assistance until it takes immediate steps to improve its rights record. "We cannot stand here and say we are troubled by hundreds of people being sentenced to death after a few minutes in a mass trial, but since we have been friends for so long we will go ahead and send you hundreds of millions of dollars in aid. No." Leahy added: "I do not think the taxpayers of this country would condone that, and neither do I." Egypt has relied for decades on American aid, which amounts to about $1.5 billion per year. Several US lawmakers in recent months, including prospective 2016 Republican presidential candidate Senator Rand Paul, have questioned the Obama administration's aid to Egypt in the aftermath of last year's overthrow of democratically-elected president Mohamed Morsi. Leahy's action came as Egyptian Foreign Minister Nabil Fahmy was visiting Washington, the highest-level Egyptian official to do so since thearmy overthrew Morsi. Fahmy met with Secretary of State John Kerry on Tuesday, and the minister is scheduled to meet Wednesday with leaders of the Senate Foreign Relations Committee.