LONDON, July 27 (Reuters) - There are still challenges to come, British Prime Minister Boris Johnson said on Tuesday in response to the International Monetary Fund revising sharply upward its growth forecast for Britain's economy this year.

"Good signs that our economy is bouncing back faster than expected, with the UK forecast to have the joint highest growth rate in the G7," Johnson wrote on Twitter.

"There are still challenges ahead and we are focused on supporting people through our #PlanForJobs." (Reporting by Costas Pitas; editing by Jonathan Oatis)