China increased its strategic crude oil reserves by 22.5 per cent between the middle of last year and the start of 2016, taking the total to 31.97 million tonnes (233 million barrels), the National Statistical Bureau said.

The volume, equivalent to about 33 days of net oil imports to China, was higher than analysts had estimated.

'Stockpiling over the second half of 2015 was faster than our calculation,' Sengyick Tee of SIA Energy said. 'The numbers look like more till the first quarter, mostly likely also including stockpiling by some independents.'

In its last update in December 2015, the government said it had 26.1 million tonnes, or about 190.5 million barrels, stockpiled by mid-2015.

The world’s largest consumer bought the crude as global prices LCOc1 sank 40 per cent in the second half of 2015 to below $40 per barrel, testing fresh multi-year lows on evidence of a growing worldwide glut.

The reserve is closely watched by analysts as a gauge of what proportion of China’s oil imports is going into the reserves and how much is being refined and consumed.

Stockpiling should pick up significantly in the fourth quarter, but slower oil demand and some delays in preparing storage tanks will likely drag on the growth rate, according to Michal Meidan of Energy Aspect.