Egypt on Friday welcomed Saudi Arabia's decision to list the Muslim Brotherhood as a terrorist organisation and called on other Arab countries to follow suit.
The Saudi move further isolates the Brotherhood of deposed Egyptian president Mohamed Morsi, already designated by Egypt as a terrorist group following a suicide bombing that killed 15 people in a police station in December.
The group condemned the bombing and has denied involvement in any of the violence rocking Egypt since Morsi was ousted by the military in July.
"We welcome the Saudi decision ... which shows the depth of cooperation and solidarity between the two countries," Egypt's foreign ministry spokesman Badr Abdelatty told AFP.
Saudi Arabia hailed Morsi's overthrow and pledged billions of dollars to Egypt's military-installed interim government.
"We look forward to see other countries which signed the 1998 Arab League counter-terrorism treaty follow the Saudi path and respect their commitments under the treaty," Abdelatty added.
The agreement has been ratified by 18 of the Arab League's 22 members, an official of the Cairo-based organisation previously told AFP.
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The Brotherhood, the largest Islamic movement in the region with a presence in most Arab countries, said it was "surprised" and "pained" by the Saudi decision.
"This new position the kingdom contrasts sharply with the history of its relations with the Brotherhood," the group said.
"History has always shown that the Brotherhood has been a leader in spreading true Islamic thinking ... without extremism, as many of the kingdom's scholars and leaders can testify."
Morsi and dozens of Brotherhood leaders face trial in Egypt on a number of charges, including collusion with militants to carry out attacks.
Among them is Yousef Qaradawi, a prominent Egyptian-born cleric based in Qatar.
The Saudi move comes two days after Riyadh, Manama and Abu Dhabi recalled their ambassadors from Doha, which supports Islamist groups in the region and was a backer of the Brotherhood.
Cairo-Doha ties have deteriorated since Morsi's overthrow and the subsequent deadly crackdown on his supporters that has left more than 1,400 dead and thousands of others behind bars.
Al-Jazeera television, based in Qatar, has also incensed Egypt's government with its coverage of the crackdown.