Amlin the biggest Lloyd's of London insurer by market value, on Thursday reported higher prices across its main markets and said earthquakes in Japan and New Zealand this year could cost it $83 million more than previously thought.

Amlin, which issued a profit warning in August due to bigger than expected catastrophe claims, said prices rose by an average of 0.9 percent as customers renewed their policies in the first 10 months of 2011, after a decrease of 1.9 percent in the same period last year.

The company also said estimated claims from the March 11 Japanese earthquake and tsunami had risen to $206 million from its previous estimate of $156 million, while its projected exposure to the quake that struck New Zealand in February had climbed to $338 million from $305 million.

While this year's performance has been impacted by an exceptionally high level and frequency of catastrophe events, the overall outlook for underwriting is improving, Chief Executive Charles Philipps said in a statement.

Amlin's shares closed at 293 pence on Wednesday, valuing the company at about 1.45 billion pounds. The stock is down 28 percent in the year to date, underperforming a 13 percent drop in the FTSE non-life insurance index <.FTAXX8530>.

(Reporting by Myles Neligan; Editing by Greg Mahlich)