Saudi Arabia's fiscal reserves dropped to a four-year low last year as the government sought to finance a budget deficit caused by plunging oil revenues, a report said Tuesday.

The reserves of the world's largest crude exporter dropped to $611.9 billion at the end of 2015, the lowest level since 2011, down from $732 billion a year before, the Saudi Jadwa Investment said in an economic report.

Jadwa said it expected reserves to fall to around $500 billion by the end of 2016, after oil prices fell by three quarters since mid-2014.

The kingdom, the second largest crude producer after Russia, posted a record budget deficit of $98 billion last year after oil income dived by 60 percent to just $118 billion.

Riyadh also projected an $87 billion deficit for this year but Jadwa forecast the shortfall to be more than $107 billion.

To help finance the budget deficit, the kingdom in December introduced a series of austerity measures raising fuel prices by up to 80 percent and increasing the prices of electricity, water, natural gas and others.

Jadwa said it expected inflation to soar this year to 3.9 percent, from 2.2 percent last year, as a result of the price hikes.

The kingdom also issued bonds in the domestic market worth $30 billion.

The International Monetary Fund last month revised downward Saudi gross domestic product growth to just 1.2 percent this year, the lowest since 2009. Its GDP grew 3.4 percent in 2015.

Saudi Arabia is currently pumping 10.2 million barrels of crude per day.