The United States has suspended deliveries of major military hardware and cash assistance to Egypt, following a deadly crackdown against protesters and the Muslim Brotherhood.

Aiming to signal its concern to Egypt's military-led government about weeks of bloodshed, Washington said Wednesday it had stopped shipments of some large-scale military systems as well as halting $260 million in cash aid to strife-torn country's armed forces.

Although the US review of its decades-old policy would not be permanent, it would remain in place "pending credible progress toward an inclusive, democratically-elected civilian government through free and fair elections," State Department spokeswoman Jen Psaki said in a statement.

Marking a dramatic break with years of unqualified support to Cairo, the decision will prevent deliveries of big-ticket items, including Apache helicopters, F-16 fighter jets, M1A1 Abrams tank parts and Harpoon missiles, officials told reporters.

They would not give specific figures, but said the value of the frozen contracts would run into "hundreds of millions of dollars in military assistance."

Washington had already effectively shelved deliveries of expensive military hardware since a July 3 coup that ousted president Mohamed Morsi and a subsequent clampdown on his Muslim Brotherhood supporters.

In the wake of the summer's events, President Barack Obama had ordered his national security team to review the total $1.5 billion in annual US aid to Egypt.

The decision had been outlined Wednesday in a 40-minute phone call between US Defense Secretary Chuck Hagel and Egypt's military chief Abdel Fattah al-Sisi, which officials described as "very friendly."

The United States, however, will keep up assistance "to help secure Egypt's borders" and bolster "counterterrorism and proliferation, and ensure security in the Sinai," Psaki said.

Washington will also continue "to provide parts for US-origin military equipment as well as military training and education," along with aid in health, education, and private sector development, she added.

After Morsi's overthrow, the Pentagon called off a planned exercise with Egypt and postponed the delivery of four F-16 fighters.

Officials stressed the US government valued its longstanding ties with Egypt and would not be cutting off all aid -- of which $1.3 billion has been devoted to military hardware and training.

"We have decided to maintain our relationship with the Egyptian government, while recalibrating our assistance to Egypt to best advance our interests," Psaki said.

"We believe the US-Egypt partnership will be strongest when Egypt is represented by an inclusive, democratically-elected civilian government based on the rule of law, fundamental freedoms and an open and competitive economy," she added.

Obama and his aides have repeatedly appealed to Egypt's military-backed government to hold fresh elections to restore democratic rule, but have so far failed to persuade Cairo to change its approach.

"This decision just underscores that the United States will not support actions that run contrary to our interests and our principles, and it is important to be clear about those things," a senior administration official told reporters.

"We've conveyed that very clearly and consistently to the Egyptian government."

Washington will now work with the Egypt to "reshape and restructure" current economic assistance programs to "directly focus more on benefiting the Egyptian people," another senior administration official said.

Funds would also be released for the Egyptian Enterprise Fund, aimed at boosting the country's private sector.

Israel, anxious about maintaining its 1979 peace accord with Egypt, had reportedly asked Washington to maintain aid to Cairo's military-led interim government.

In drawing up the list of hardware placed on hold, the administration had paid special attention to counter-terrorism efforts, especially in the Sinai peninsula, and border security.

It had taken "a step back to look at what really is necessary in this environment to address the vital security of both countries," a third administration official said.

"There will be no diminution in Egypt's ability to be a strong security partner to the United States," he added.