Gulf Arab oil exporters are expected to see their budget deficits peak this year owing to the plunge in energy revenues, a report said on Tuesday.
The combined deficit of the six Gulf Cooperation Council (GCC) states is forecast to hit $153bn in 2016, up from $119bn last year, Kuwait's investment firm KAMCO Research said.
Opec kingpin Saudi Arabia is expected to account for 55%, or more than $84bn, of the shortfall.
Last year, the world's top crude exporter posted a record deficit of $98bn.
The GCC deficit will start easing from next year but the six nations are forecast to post an average annual shortfall of $100bn until 2021, the report said.
The GCC countries together pump more than 18mn barrels per day of crude oil.
GCC total revenues, mainly from hydrocarbons, dropped from a peak of $735bn in 2013 to just $443bn in 2015, the lowest in five years, KAMCO said.
They are forecast to slide further to $365bn this year, the report said.
Oil prices have plunged from well over $100 a barrel in mid-2014, dropping below $30 a barrel at the start of this year before recovering to the $40-50 range.
Crude prices slumped due to persistent oversupply and a sluggish global demand amid fierce competition among producers to preserve their market share.
The gloomy economic forecasts for the Gulf oil exporters come despite a series of austerity measures that included reducing subsidies on power, fuel and other services in a bid to cut spending and raise non-oil revenues.
GCC states cut their public spending from $615bn in 2014 to $563bn last year. A further drop to $519bn is expected this year, KAMCO said.
The International Monetary Fund has welcomed the austerity measures but warned that greater efforts are needed to plug budget deficits.