Protesters have once again blocked the entrance to Iraq's Umm Qasr commodities port near Basra.
The standoff is preventing employees and tankers from entering and has brought operations down by 50%.
One source told Reuters if it continues operations will come to a complete halt by the end of the day.
Since anti-government protests began early October the port has been blocked twice before.
Umm Qasr is Iraq's main Gulf port.
It receives imports of grain, vegetable oils and sugar shipments that feed a country largely dependent on imported food.
The first time it got shut down a government spokesman said the blockage cost the country more than $6 billion during just the first week of the closure.
But protesters who are demanding the overthrow of a political class seen as corrupt and beholden to foreign interests have shown no sign of backing down.
Despite the fact more than 300 people have been killed around the country since the unrest began.