London (AFP) - Britain's state-rescued Royal Bank of Scotland posted a surge in profits on Friday, boosting its share price, but warned over future earnings.
Net profit almost tripled to Â£1.425 billion ($2.42 billion, 1.8 billion euros) in the six months to the end of June, compared with the same period in 2013, the bank said.
Pre-tax profits jumped 93 percent to Â£2.65 billion, it added.
In reaction, RBS shares rocketed 14.34 percent to 376 pence, topping London's benchmark FTSE 100 index, which was flat at 6,816.25 points in early trading.
"These results show that underneath all the noise and huge restructuring of recent years, RBS is a fundamentally stronger bank that can deliver good results for customers and shareholders," said chief executive Ross McEwan.
"But let me sound a note of caution. We are actively managing down a slate of significant legacy issues.
"This includes significant conduct and litigation issues that will likely hit our profits going forward. I am pleased we have had two good quarters, but no one should get ahead of themselves here -- there are bumps in the road ahead of us."
The Edinburgh-based bank is 81-percent state-owned after it was rescued with Â£45.5 billion of British taxpayers' cash during the 2008 global financial crisis, making it the world's biggest-ever banking bailout.