Birol and Barkindo said they expect developing countries to see their oil and gas income fall by 50% to 85% in 2020.
They singled out public sector spending in vital areas such as healthcare and education as being especially vulnerable.
Their prediction comes at a time crude oil prices have fallen by about 30% due to a price war between Russia and Saudi Arabia.
Oil prices slid 10% in the previous session, as the coronavirus continues to spread worldwide, and amid an ongoing price war between OPEC kingpin Saudi Arabia and non-OPEC leader Russia.
Crude futures have more than halved since climbing to a peak in January.
On Monday, Saudi Arabia’s state-owned oil giant, Saudi Aramco, said it would likely continue with a planned oil production hike from April into May, reportedly suggesting it was “very comfortable” with an oil price of $30 a barrel.
Russia, which refused to sign up to OPEC’s proposal of deeper production cuts earlier this month, has claimed it can withstand lower oil prices for as long as a decade.
OPEC’s Barkindo and the IEA’s Birol, did not address Russia specifically in their joint statement, but both “underscored the importance of market stability, as the impacts of extreme volatility are felt by producers.”
They agreed to “remain in close contact on the matter” and continue their regular consultations on oil market development.