Most Middle Eastern stocks ended lower on Monday as a fast-spreading new coronavirus strain in Britain fuelled concerns that a resurgence of infections could stunt the pace of reopening economies.
The variant, which officials say is up to 70% more transmissible than the original, also prompted concerns about a wider spread.
Brent crude slid $3, or 5.7%, to $49.26 a barrel by 1028 GMT after rising 1.5% and touching its highest since March last Friday.
Saudi Arabia's benchmark index concluded 1.7% lower, with petrochemical firm Saudi Basic Industries and Al Rajhi Bank 1120.SE dropping 2.8% and 0.8%, respectively.
The kingdom suspended late on Sunday all international commercial flights for a renewable week except for the foreign flights already in Saudi Arabia which will be allowed to leave, state news agency SPA reported quoting an interior ministry source.
Dubai's main share index closed 3.9% lower, with sharia-compliant lender Dubai Islamic Bank declining 4.5%, while blue-chip developer Emaar Properties retreated 4.8%.
Elsewhere, DXB Entertainment slid 5%.
Dubai property company Meraas, which owns more than half of DXB Entertainments, intends to make a conditional offer to acquire the remaining shares in the loss-making theme park group and take it private, stock exchange filings showed on Sunday.
The Abu Dhabi index fell 0.8%, weighed down by a 3.1% fall in Aldar Properties and a 4.6% decline in Abu Dhabi Islamic Bank.
In Qatar, the index slipped 0.4%, with Qatar Fuel shedding 2.6%.
Meanwhile, the Gulf state's Ministry of Public Health approved on Sunday the Pfizer and BioNTech COVID-19 vaccine for emergency use, Reuters reported, citing Qatar state news agency QNA's tweet.
Outside the Gulf, Egypt's blue-chip index clawed back some losses to trade down 2.8%, with top lender Commercial International Bank dropping 0.8%.
In early trading, the Egyptian bourse halted trading on the EGX100 after the index fell by 5%.
(Reporting by Maqsood Alam in Bengaluru, editing by Louise Heavens) ((Maqsood.Alam@thomsonreuters.com;))