Oil inventories have swelled to the highest level on record as crude producers intensify the battle for market share, putting unprecedented strain on the world’s energy infrastructure.

The International Energy Agency, the west's oil forecaster, said stocks in developed countries had ballooned to almost 3 billion barrels – the equivalent of more than a month's supply of global oil consumption.

Even though demand has been robust this year, crude inventories have continued to rise at more than 1 million barrels a day, with storage tanks filling quickly and lines of ships forming at key ports.

As a result oil prices, which have halved in the past 18 months, could fall even further to encourage refiners to process more crude and force more production offline, traders said.

Brent crude, the global benchmark, fell to below $44 a barrel yesterday.