Saudi Arabia will trim this year's budget by around five percent, the finance minister said, in its first austerity measure as the economy reels from the fast-spreading coronavirus and crashing oil prices.

Saudi Arabia is bracing for an economic slump after it shut down cinemas, malls and restaurants, suspended the year-round umrah pilgrimage and locked down eastern Qatif region -- home to around 500,000 people -- in a bid to contain the deadly coronavirus.

The world's top crude exporter also faces plunging oil prices, the mainstay of government revenue, which slipped below $25 a barrel this week to touch 18-year lows on the back of sagging demand and a price war with Russia.

"The size of the partial reduction ... has reached approximately 50 billion riyals ($13.32 billion), which represents less than 5 percent of the total expenditures approved in the budget for 2020," said Finance Minister Mohammed al-Jadaan.

In a statement released by the official Saudi Press Agency late Wednesday, the minister added the cuts would have "the least social and economic impact".

But the economic consultancy Nasser Saidi and Associates has reported the cuts will be deeper, saying the finance ministry has instructed various government bodies to submit proposals to slash this year's spending by 20 to 30 percent.

The Energy Intelligence Group says the kingdom has asked government bodies to prepare budget scenarios in which crude prices could drop as low as $12-$20 per barrel.

The deep-pocketed kingdom, with fiscal reserves of around $500 billion, has reiterated it is an ultra low-cost producer of crude and can withstand low prices for years.

But Riyadh has posted a budget deficit every year since the last oil price rout in 2014. It has borrowed over $100 billion and drawn from its reserves to plug the deficit.

Late last year, the kingdom projected a budget deficit of $50 billion in 2020 as spending was projected at $272 billion.

The budget shortfall is expected to jump substantially as crude prices decline.

Saudi Arabia needs a crude price of about $80 a barrel to balance its budget.