PARIS (AFP) - International Monetary Fund chief Christine Lagarde said Friday the plunge in global stock exchanges this week was due to a market "over-reaction".

"Generally the IMF doesn't comment on short-term market variations (but) we can't help ourselves from thinking we're in the presence of a correction and maybe at this stage an over-reaction," she said.

Markets have plunged this week on fears that the euro crisis could be resurfacing, the Ebola virus and geopolitical worries.

European markets bounced back sharply on Friday, however, with Frankfurt up more than three percent, the French market up nearly 3 per cent and London higher by just shy of 2 per cent.