* Insurer's results top estimates
* AXA acquisition drives premiums, underwriting improves
* AXA business to be fully integrated by mid-2013
TORONTO, May 1 (Reuters) - Intact Financial said its first-quarter operating profit rose 75 percent, topping estimates, as insurance premiums rose due to last year's acquisition of French insurer AXA's Canadian assets.
Intact, Canada's largest property and casualty insurer, said on Tuesday it earned C$179 million ($180 million), or C$1.34 a share, compared with a year-before profit of C$102 million, or 91 Canadian cents a share.
Analysts had expected an operating profit of C$1.26 a share, according to Thomson Reuters I/B/E/S.
On a net basis, which includes integration costs related to the C$2.6 billion AXA transaction, profit rose to C$177 million from C$157 million.
Intact, the former Canadian insurance arm of Dutch financial group ING, sells insurance under the Belair Direct and Grey Power banners.
The Toronto-based company said the results were helped by mild winter conditions across much of Canada, which reduced claims frequencies across all of its business lines, as well as stronger investment gains.
Direct premiums written jumped 49 percent to C$1.4 billion, while underwriting income more than doubled to C$123 million, up from C$58 million.
Intact said the integration of the AXA business is on track to be completed by mid-2013.
The company's stock, the top Toronto-listed financial performer in 2011, closed at C$63.38. The results were released after markets closed.