Policy renewal prices rose an average 4 percent last month, Amlin said on Tuesday, compared with a 1.3 percent decline a year earlier.
The increase was driven by its catastrophe reinsurance business, where prices for business written in London and Bermuda rose an average 15.9 percent.
Unprecedented catastrophe loss activity in 2011 has prompted a notable uplift in reinsurance rates, Amlin said.
The insurance industry absorbed claims of $108 billion (68 billion pounds) from disasters including Japan's Tohoku earthquake in 2011, making it the second-costliest catastrophe year after 2005, when Hurricane Katrina devastated New Orleans, according to reinsurer Swiss Re.
There has been speculation the losses could force less well-funded players to retrench, easing competitive pressures and reversing a four-year decline in insurance prices, although most analysts say any big increase will likely be limited to catastrophe-related business.
Separately, rival insurer Beazley
Amlin, the biggest listed insurer operating in the Lloyd's of London market, also said it expected to take a hit of 50-70 million pounds from last year's Thai floods, while its loss from the Cost Concordia shipwreck would be below 10 million.
Premium income for the year to date is 746 million pounds, up 19.2 percent, the company said.
Amlin shares were 1.1 percent higher at 341 pence by 8:35 a.m., outperforming a 0.1 percent rise in the Stoxx 600 European insurance index <.SXIP>
(Reporting by Myles Neligan; Editing by Dan Lalor)