Dozens of merchant ships with grains and sugar are stuck outside Iranian ports after weeks of delays as payments snags disrupt flows of goods into the country, according to trade sources and shipping data.

Food is exempt from the West’s sanctions on Iran over its nuclear program, but the impact of the sanctions on Iran’s financial system have created complex and erratic payment arrangements with international companies.

The latest payment issues have led to ships being unable to discharge cargoes, with at least 40 bulk carrier ships stuck outside the major Iranian ports of Bandar Imam Khomeini and Bandar Abbas, ship tracking data on Refinitiv showed.

Iran’s foreign ministry was not immediately available for comment.

Iran’s Ports and Maritime Organization said in a report in November that some 37 ships loaded with 2.2 million tons of goods had not been able to unload due to “documentation and hard currency payment issues” at Bandar Imam Khomeini.

Food security is a priority for Iran and the need for imports has increased because of a drought which has hit domestic food production for two seasons in a row.

Iran is expected to import 5.5 million tons of wheat in 2022/23 season (July/June), down from 8.0 million in the prior season but still well above normal levels, based on US Department of Agriculture data.

In the previous five seasons, imports had averaged just 1.1 million tons, the data showed.

Iran has been rocked by months of unrest, in which demonstrators from all walks of life have called for the fall of Tehran’s ruling theocracy, and has posed one of the biggest challenges to the republic since its 1979 revolution.

One Western trade source familiar with the matter estimated that the cargoes stuck outside Iran’s port are worth more than $1 billion with charterers of the cargoes also facing delay costs known as demurrage.

Broker Paragon Global Markets (PGM) said it was not clear how many of the vessels might have sugar cargoes onboard.

“That is potentially bearish if a large buyer can’t find money, then that could leave a large quantity of sugar trying to find a home,” PGM said in a note.

Iran’s sugar imports are expected to total 1.1 million tons in the 2022/23 season (October/September), slightly down from 1.3 million in the prior season, according to the International Sugar Organization.