British insurer Aviva on Thursday said it had swung back into profit during 2013 as it underwent major restructuring and after it avoided a huge write-down suffered the previous year. Chief executive Mark Wilson warned against "complacency", while Aviva said it had been hit by claims totalling £60 million ($100 million, 73 million euros) so far this year following severe flooding across Britain. But investors cheered the results, sending Aviva's share price rocketing on London's benchmark FTSE 100 index. Net profit stood at £2.0 billion last year compared with a loss after tax of £3.1 billion in 2012, the company announced in a results statement. Aviva had slumped into a huge loss during 2012 owing mainly to a massive write-down following the sale of its US business. "The turnaround at Aviva is intensifying," Wilson said in the statement. "Following our exit from a number of low margin, underperforming or non-strategic businesses, Aviva is simpler, more focused and better managed. We have significantly improved our capital surplus, increased our liquidity and have a stronger leadership team. "Although we have made progress in 2013, I want to guard against complacency." Aviva on Thursday added that operating profit -- an indicator of its day-to-day business -- rose 6.0 percent to £2.04 billion in 2013 compared with the previous year thanks to a jump in sales of new insurance policies. Shares in Aviva shot 8.35-percent higher to 505 pence in London morning trade. "Aviva remains a recovery story," said Richard J Hunter, head of equities at Hargreaves Lansdown Stockbrokers. "Whilst the stock is a fair way off its historic highs, it appears that the travails of more recent times have been parked for now. "The shares have had a good run to reflect the progress which has been made, having risen 31 percent over the last year, as compared to a 5.0-percent hike for the wider FTSE 100," he added.