King Abdullah of Saudi Arabia has called on Arabs to stand together against "attempts to destabilise" Egypt.
"The Kingdom of Saudi Arabia, its people and government stood and stands by today with its brothers in Egypt against terrorism," he said in a statement read on state TV on Friday, backing Egypt's military leadership.
"I call on the honest men of Egypt and the Arab and Muslim nations ... to stand as one man and with one heart in the face of attempts to destabilise a country that is at the forefront of Arab and Muslim history," he added.
He also said that they were confident that Egypt will recover.
Saudi Arabia was a close ally of former President Hosni Mubarak and has historically had a difficult relationship with the Muslim Brotherhood.
It pledged $5bn in aid to Egypt after Mohamed Morsi of the Brotherhood was ousted from the presidency last month.
Saudi Arabia "has stood and stands with its Egyptian brothers against terrorism, deviance and sedition, and against those who try to interfere in Egypt's internal affairs... and its legitimate rights in deterring those tampering with and misleading" its people, he said.
H A Hellyer from the Brookings Institution and the Royal United Services Institute, speaking from Cairo, said Saudi Arabia would back whoever they think can actually hold on to order in the country.
"At present that seems to be the interim government as well as the military. Also Saudi Arabia has a very uncomfortable history with the Muslim Brotherhood" he told Al Jazeera.
Meanwhile, with fresh violence erupting across Egypt, the Cairo leadership said it was confronting a "malicious terror plot" by the Muslim Brotherhood.
World leaders react strongly to bloody developments in Egypt
Egypt has faced international condemnation since nearly 600 people were killed in clashes on Wednesday when police broke up protest camps of supporters of Morsi, in Egypt's bloodiest day in decades.
The kingdom's regional arch foe Iran had condemned what it called Wednesday's "massacre" in Egypt.
But Arab states of the Gulf - the United Arab Emirates and Bahrain - have separately voiced support for the deadly assault on Morsi's supporters, saying it was the state's duty to restore order.
They, along with Kuwait, also welcomed the July 3 army coup that ousted Morsi, Egypt's first elected leader since an popular uprising in 2011 toppled Mubarak.