Saudi Arabia's reserves of easily recoverable oil have long been the world's largest.

For nearly 30 years - despite rising production, large swings in oil prices and improved technology - Riyadh has annually reported the same number for reserves at around 261 billion barrels, according to a statistical review by BP.

Saudi Energy Minister Khalid al-Falih is due to hold a news conference in Riyadh on Wednesday to make the announcement at around 11.30 local time (0830 GMT).

He is also expected to provide further updates on the country's energy strategy.