The head of the International Monetary Fund is warning that the global economy is losing momentum and urging governments to take action to preserve the recovery.

Christine Lagarde said in a speech Tuesday in Frankfurt, Germany, that "the recovery remians too slow, too fragile."

She said that the global economy isn't in a crisis — and that's good news. She said, however, that slow growth risks becoming ingrained as a "new mediocre."

She said the global outlook has weakened over the next six months, suggesting the IMF may be revising its growth outlook. The speech sets the stage for the IMF and World Bank meetings in Washington later this month.

Lagarde urged governments to take pro-growth reforms and to increase spending on public infrastructure.