The fallout from the war in Ukraine could cut global economic growth by "over one percentage point" in the first year after the invasion, the OECD said in a report on Thursday.
The impact "if sustained" would produce "a deep recession in Russia, and push up global consumer price inflation by approximately 2.5 percentage points", the group of developed economies said in its report.
Outside Russia and Ukraine, the pain would be felt most in Europe, with growth impacted by up to 1.4 percentage points in the eurozone, according to the Organisation for Economic Co-operation and Development.
The continent is highly dependent on supplies of raw materials, food and energy from Russia and Ukraine, the prices for which have been sent rocketing by the conflict.
Those countries "that have a common border with either Russia or Ukraine" would feel the impact most, while bearing the brunt of refugee flows from Ukraine, the OECD said.
Governments could mitigate the impact to the economy with "targeted fiscal support", without fuelling faster price rises too much.
The extra push to inflation comes at a time when the pace of price rises around the world is already elevated.
On Wednesday, the US Federal Reserve announced a quarter-point increase to its benchmark interest rate to respond to runaway inflation.
Central banks should continue with their pre-crisis policies in the face of the uncertainty caused by the conflict, the OECD said.
It also warned against the risk of a "sharp increase in poverty and hunger", particularly in developing economies, were supplies of wheat from Russia and Ukraine to be cut off completely.
