DUBAI (Reuters) - Oman, traditionally on friendly terms with Iran, confirmed on Thursday that it had joined a Saudi-led coalition of Muslim countries fighting terrorism, a move praised by other Gulf Arab states as closing ranks with them against Iran.
Saudi and Gulf sources reported the development on Wednesday, saying Omani Minister for Defence Affairs Badr bin Saud al-Busaidi had informed Saudi Arabia in a letter that it would join the 40-strong grouping.
On Thursday, the Omani Foreign Ministry said in a statement that the move "comes within the common understanding of the Islamic countries and in particular the role and leadership of the sisterly Kingdom of Saudi Arabia".
The ministry added, without elaborating, that Oman would also join hands with "brothers and friends" for regional security and peace.
Although differences are rarely aired in public, Oman has long stood out among its Gulf allies. The Sultanate has worried that a wider regional confrontation between Riyadh and Tehran could threaten its own stability, and has often sought to play the conciliator.
Saudi Arabia announced the formation of the coalition in December 2015 to the satisfaction of Washington, which had been urging greater regional involvement in the campaign against the militants of Islamic State, who control swathes of territory in Iraq and Syria.
Although not explicitly targeted at Iran, the coalition includes neither Iran nor Iraq, whose Shi'ite-led government is closely allied with Iran.
Oman has watched anxiously as rivalry between Sunni Muslim Saudi Arabia and Shi'ite Iran has grown. Riyadh and some other Gulf Arab states accuse Tehran of interfering in Arab countries to build its influence. Iran denies that accusation.
Reporting by Ahmed Tolba in Cairo and Celine Aswad in Dubai, Editing by William Maclean and Kevin Liffey