(CNN) The United Arab Emirates on Thursday upped the ante against Qatar by shutting its airspace, not just to Qatari flights but all air traffic to and from the capital Doha amid the worst diplomatic crisis to hit Gulf Arab states in decades.
The move comes as Bahrain criminalized any show of support on social media in a bid to further isolate Qatar, which has been accused of supporting terrorism and destabilizing the region.
Saudi Arabia, Bahrain, Egypt and the United Arab Emirates this week broke off relations with Qatar, which has dismissed the accusations as "unjustified" and "baseless." Yemen and the Maldives also cut ties with Qatar. The list later expanded to nine, with the addition of Mauritius, Mauritania and Libya's eastern-based government.
On Thursday, the UAE General Civil Aviation Authority said via Twitter: "We ... have closed the airspace for all Air Traffic to and from Doha until further notice. #GCAA #UAE". A day earlier, the authority shut down all offices in the UAE of Qatar's national carrier Qatar Airways.
Bahrain's move against Qatar is in step with other members of the Gulf Cooperation Council, a close regional alliance that includes Saudi Arabia, the UAE, Oman, Kuwait and Qatar. Only Kuwait and Oman continue ties with Qatar.
A statement from Bahrain's Interior Ministry said that relations had strained because of Qatar's "hostile activities" and that any show of sympathy for the Qatari government or against Bahrain's action on social media will be "considered a crime" and punishable by a jail term of up to five years and a fine.
Qatari citizens have been told they have 14 days to leave Saudi Arabia, Bahrain and the UAE, and those countries banned their own citizens from entering Qatar.
In a statement, UN Secretary-General António Guterres said he was deeply concerned about the situation and offered support in resolving the crisis via diplomatic channels.
Gulf allies have repeatedly criticized Qatar for alleged support of the Muslim Brotherhood, a nearly 100-year-old Islamist group considered a terrorist organization by Saudi Arabia and the UAE.
The UAE accused Qatar of "funding and hosting" the group in its statement announcing the severance of ties.
It also cited Qatar's "ongoing policies that rattle the security and sovereignty of the region as well as its manipulation and evasion of its commitments and treaties" as the reason for its actions.
Qatar's foreign minister has insisted his country was combating terror financing and "protecting the world from potential terrorists."