The Bank of England expects to consider raising interest rates in 2015, a year earlier than expected, following a sharp fall in unemployment.

But the bank tempered expectations of an early increase with the warning that the recovery remained fragile and rates could still remain low for several years.

Governor Mark Carney said he expected growth to remain modest over the next couple of years while the economy continues to be hampered by a weak banking sector and stumbling overseas markets.

Speaking after publication of the central bank's quarterly inflation report, Carney played down concerns that the current 0.5% base rate would rise before real incomes begin to rise and the recovery is secured.

"The economy is growing robustly as lifting uncertainty and thawing credit conditions start to unlock pent-up demand. But significant headwinds – both at home and abroad – remain, and there is a long way to go before the aftermath of the financial crisis has cleared and economic conditions normalise," he said in the report.

"That underpins the monetary policy committee's (MPC) intention to maintain the exceptionally stimulative stance of monetary policy until there has been a substantial reduction in the degree of economic slack."

In August the BoE said as part of its new policy of forward guidance that it would not consider raising interest rates before unemployment fell to 7%. MPC members agreed that unemployment was a strong indicator of slack in the economy. Figures for August show that rate has fallen to 7.6% following an unexpectedly sharp rise in job recruitment over the previous three months.

In response the BoE said there was now a three in five chance that the UK unemployment rate would hit 7% in mid-2015 compared to a previous prediction of late 2016.

Deputy governor Charlie Bean said forward guidance was still pointing to a rate rise later rather than sooner. He said: "The key message is that policy is not going to be related to growth rates but the elimination of slack."