CARACAS (Commodity Online) : US Geological Survey on Sunday said Venezuela's Orinoco oil belt holds 513 billion barrels of recoverable heavy crude, nearly twice as much as the proven reserves of Saudi Arabia.

In its latest estimate the US Geological Survey said the area had the largest accumulation it had ever assessed.

According to the estimates, the assessments based not on estimated reserves that could be certified but on 'what could be recoverable with the technologies that we're aware of today.

However, there was no immediate reaction from the state oil company Petroleos de Venezuela (PDVSA), which has said it hopes to eventually certify more than 235 billion barrels of crude in the Orinoco River basin in eastern Venezuela.

US Geological Survey team relied in part on data from PDVSA, which has said the Orinoco River basin could hold 1.3 trillion barrels of extra-heavy crude, only some of which is feasible to pump from subterranean sandstone reservoirs.

The estimate was based on the ability to recover 40 to 45 per cent of the oil in the ground.

Venezuela boasts the largest proven reserves outside of the Middle East, 172 billion barrels, but still trails Saudi Arabia, which has proven reserves of more than 260 billion barrels.

The Latin American country made it a priority to gradually increase Venezuela's proven reserves, particularly in the Orinoco oil belt.