Saudi King Abdullah pledged his country's support to Egypt's fight on "terrorism," saying it was the military-backed government's "legitimate right," in a speech aired on official Al-Ekhbariya television Friday.

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.

As he made his remarks, with fresh violence erupting across Egypt, the Cairo regime said it was confronting a "malicious terror plot" by the Muslim Brotherhood.

Egypt has faced international condemnation since nearly 600 people were killed in clashes on Wednesday when police broke up protest camps of supporters of ousted president Mohamed Morsi, in Egypt's bloodiest day in decades.

King Abdullah urged the Arab and Muslim world to stand "in the face of whoever tries to destabilise" Egypt.

"Those who have interfered in its affairs must know that they are causing sedition and backing terrorism, which they claim to fight," said the head of oil-rich conservative kingdom that is a major regional player.

Saudi Arabia welcomed Morsi's ouster, and King Abdullah was the first foreign head of state to congratulate Egypt's interim president Adly Mansour hours after his appointment.

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 long-time president Hosni Mubarak -- a close Saudi ally.

Following Morsi's ouster, Saudi Arabia, the UAE, and Kuwait pledged a combined total of $12 million in aid to support Egypt's faltering economy.

Qatar, a key supporter of Egypt's Muslim Brotherhood, has so far been the only Arab state of the Gulf to strongly condemn Wednesday's crackdown.