The Saudi stock index dropped 0.5 percent in active trade as real estate firm Dar Al Arkan, the most heavily traded stock, plunged 10 percent. It had more than doubled in price in the last quarter of 2017.

Bus operator Saudi Public Transport Co, which could benefit if driving of private cars is curbed by higher gasoline prices, gained 3.6 percent. Car rental company Budget Saudi fell 2.6 percent.

Telecommunications firm Mobily was a big gainer, jumping 8.6 percent in its heaviest trade since October 2015.

The energy ministry had already indicated that it would announce in the first quarter of this year a rise in gasoline prices, but the rise came earlier than some people had expected.

Some had expected authorities to wait to gauge the blow to consumption from the introduction of a 5 percent value-added tax at the start of this year. Together, the tax and higher gasoline prices could affect consumption significantly, although Riyadh is also introducing a system of cash handouts to lower- and middle-income households to soften the pain of reforms.

The price of Octane 91 gasoline rose to 1.37 riyals (37 US cents) a litre from 0.75 riyal, while Octane 95 rose to 2.04 riyals from 0.90 riyal. Diesel rates for trucks were left unchanged. Saudi Arabia's gasoline prices will still be among the lowest in the world.

Other major Middle Eastern stock markets were closed for New Year holidays on Monday.