Seventy percent of China's oil needs will come from imports by 2020, with the bill expected to land at a record $500 billion (375 billion euros) as rapid economic growth is spurring car sales, a study showed on Tuesday.

In the report, British advisory firm Wood Mackenzie said Chinese crude oil imports will surpass that of the United States in 2017 and are expected to reach a total of 9.2 million barrels of oil per day in 2020.

At the same time, it said US oil import requirements will shrink to 6.8 million barrels of oil per day, or a spend of around $160 billion from its peak of $335 billion, mainly on the back of falling demand and an increase in domestic supply and a growth in imports from Canada.

"We will therefore see OPEC suppliers, who traditionally focused on the US for crude sales, compelled to shift their focus towards China," said William Durbin, the group's Beijing-based president of global markets.

The firm estimates that Chinese imports from the Organisation of the Petroleum Exporting Countries (OPEC) will grow to 66 percent from the 52 percent recorded in 2005.

Oil market analyst Harold York said the jump in Chinese imports can largely by attributed to domestic oil demand growth and is "driven by gasoline demand due to the near-exponential increase in personal auto vehicles and diesel demand related to commercial trucking as China's economy grows."

"By 2020 China will be second only to the US for the total fleet of personal auto vehicles in use. From 2005-2020, China will see the number of vehicles rise from 20 million to 160 million," he said.

China is already the biggest energy user in the world and the second-largest oil consumer after the United States.

Last week, the US Energy Information Administration (EIA) said that from October, China is set to overtake the US as the world's largest net oil importer.