Laying out a broad spectrum of risks, from refugee crises and rising protectionism to climate change, the leaders of the two powerful global development banks called for the most developed countries especially to take "immediate" action to stimulate growth to avoid backsliding into a worldwide stall.
"In the global economy, there are not many bright spots," said World Bank President Jim Yong Kim. "The weakening global economy threatens our progress toward ending extreme poverty by 2030."
"We are on alert, not alarm," she said. "The current policy responses that we are seeing need to go faster and need to go deeper."
Both noted the rise in the need to support weak economies, many battered by the crash in the prices of oil and other commodities.
"The demand for our services has never been higher outside of a crisis period," Kim said, saying the Bank expects middle income countries will need some USD 25 billion in loans this year, USD 10 billion more than the bank had previously anticipated.
Last week Angola, its finances battered by the plunge in oil prices, requested a three-year bailout program from the Fund.
The IMF opened the week by cutting its forecast for world economic growth for the third time in six months, saying growth has been "too slow for too long."
The Fund lowered its growth forecast for 2016 to 3.2 percent, compared to the 3.8 per cent it expected a year ago.
"Lower growth means less room for error," IMF chief economist Maurice Obstfeld said.
"The weaker is growth, the greater the chance that the preceding risks, if some materialize, pull the world economy below stalling speed."
If not countered with more pro-growth measures, the combination of low growth, low inflation and high debt could combine to push the world economy toward the edge of recession, the IMF warned.
One key danger, Lagarde said today, is the possibility of Brexit, a British exit from the European Union.
"It's been a long marriage between members of the European Union," she said.
