The underwater pipelines that connect storage tanks near the southern Basra oil terminal to offshore tanker fuelling terminals need urgent replacement or repair, the newspaper said on Wednesday, citing a previously undisclosed notification to the US Congress.

‘The likelihood of a worst-case catastrophic failure, subsequent collapse of Iraqi crude oil export revenue resulting in a devastating drop in the Iraqi GDP, global economic market impacts and a possible ecological and environmental disaster should warrant concern,’ the document obtained by the FT said.

Iraq's oil minister told the financial daily that the country was very conscious of its need to expand its export facilities in the south.

The document said oil experts from the US Army Corps of Engineers and at Iraq's South Oil Company have concluded, based on information available, that the two 48-inch crude export lines could potentially cease to function at any time.

The 50 km pipelines were said to be suffering from ‘severe corrosion’.

The report obtained by the FT said that an upgrade of the pipelines could cost up to $5 billion.

‘The pipes are 10-20 years past their useful life and are operating at roughly 25 percent of their designed capacity.’

Iraqi oil exports fell in September, averaging 1.61 million barrels per day (bpd), compared with 1.83 million bpd in August, according to Reuters data.