Euro zone business activity picked up to a five-month high in January, a key survey showed today, just the day after the European Central Bank announced its more than €1 trillion stimulus package.

Markit Economics said its Composite Purchasing Managers Output Index (PMI) for the 19-nation single currency bloc hit 52.2 points, up from 51.4 in December.

Any reading above 50 points shows activity is expanding and the January report is a welcome sign that a modest turnaround is holding after the economy faltered for most of 2014.

The euro zone stagnated in the second quarter last year and only managed 0.2% growth in the three months to September, with analysts worried that deflation could tip the economy back into recession.

Markit chief economic Chris Williamson said the latest PMI figures marked "a positive start to 2015, but the rate of expansion remains worryingly weak."

The report would suggest the euro zone was growing "at a quarterly rate of just 0.2% and the economy both fragile and susceptible to shocks and further setbacks," Williamson said.

"That said, there's good reason to believe the rate of expansion will continue to improve in coming months," he said, citing signs of a rise in business confidence while tumbling oil prices should cut costs and help boost consumer demand.

The ECB said yesterday it would pump some €60 billion a month up until September of next year into the economy with its bond purchase programme in an effort to get it back on track.