Revenue losses for oil producers in the Middle East and North Africa could reach $300 billion because of price declines, the International Monetary Fund said.

Oil prices are down around 50 percent from the June 2014 highs. The decline means a source of de facto stimulus for countries that rely in oil imports, but is problematic for those that rely on oil exports for most of their government revenues.

Masood Ahmed, director of Middle East programs at the IMF, said Middle East and North African oil producers are expected to be out about $300 billion, or 21 percent of their collective gross domestic product, because of the steep decline in oil prices.

In the short term, most oil producers will draw on financial reserves to cope with the weak price market.

"However, with a more constrained fiscal outlook over the next few years, oil exporting countries would need to adapt progressively to new realities," Ahmed said in a Thursday statement.

Most countries in the region are expected to run a deficit this year. The six members of the Gulf Cooperation Council -- all on the Arabian Peninsula -- are expected to move from surplus to deficit, erasing nearly 11 percent of their combined GDP.

Ahmed said oil exporting countries will need to focus on mid-term stresses and, if the low price of oil persists, they'll need to learn to cope with what he said was a new reality in the global oil market.

"Spending will need to be better prioritized to ensure it is efficiently meeting social and economic development objectives and options for increasing non-oil revenues should be considered," he said.