The sharp drop in oil prices, if sustained, is likely to pull down sovereign ratings of exporter countries with weaker finances and especially those with the added pressure of pegged exchange rates, rating agency Fitch said on Tuesday.

Fitch’s top the Middle East and Africa sovereign analyst Jan Friederich told Reuters that with the oil prices likely to stay low for some time, countries from Saudi Arabia, Iraq, and Oman to Nigeria and Angola were all in focus.

“Countries that are in a somewhat vulnerable external position and have a fixed exchange rate are of course particularly vulnerable,” Friederich said.

On individual countries, he said Saudi Arabia’s financial reserves and its sovereign wealth fund provided a buffer but that there was not “infinite leeway” in the country’s A (stable) rating for the buffers to disappear.

A continued rise in government debt in Oman “would be a concern” he added, while Nigeria’s B+ (negative) rating could face problems if a “prolonged attempt” to defend the country’s currency peg ate heavily into its international reserves.

Commodity dependence is most pronounced globally in Angola, Iraq, Suriname and Gabon, Fitch analysis shows and there are a dozen more developing countries for whom commodities exceed 70% of foreign-currency income. (Reporting by Marc Jones; editing by Saikat Chatterjee)