Gulf neighbours the United Arab Emirates and Saudi Arabia on Tuesday announced a joint committee to confront "regional challenges", in a statement published on official Emirati news agency WAM.
The move came as Saudi Foreign Minister Prince Saud al-Faisal met UAE Crown Prince Sheikh Mohammed bin Zayed al-Nahayan in Abu Dhabi.
Both the UAE and Saudi Arabia have cracked down on Islamists accused of links to groups such as the Muslim Brotherhood and the Al-Qaeda-affiliated Al-Nusra Front fighting in Syria.
Riyadh has designated both groups "terrorist" organisations.
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The newly formed "supreme committee" will be overseen by the Saudi and UAE foreign ministers, WAM said.
It will "implement the strategic vision of the leaderships of both countries to increase security and stability to face regional challenges," WAM reported.
Tensions have been running high between Saudi Arabia and the UAE on one side, and Qatar on the other. All belong to the six-nation Gulf Cooperation Council.
In an unprecedented escalation in March, Saudi Arabia, the UAE and Bahrain pulled their ambassadors from Qatar after accusing it of meddling in their internal affairs, a charge Doha dismissed.
Qatar is accused of supporting the Muslim Brotherhood, to which Saudi Arabia and other Gulf monarchies have long been hostile.
They fear its brand of grass-roots activism and political Islam could undermine their own authority.