Europe markets open strong

LONDON, England (CNN) - European markets opened higher on Monday, coming after a weekend in which world leaders promised to shore up financial markets.

Just before markets opened, the British Treasury announced a multi-billion dollar investment in three of the country's largest banks.

In early trading, London, Paris and Frankfurt were all up at least 5 percent.

One economist said he expects European markets to post strong gains on Monday after the leaders of 15 European nations agreed to a wide-ranging plan to shore up troubled banks over the weekend.