(Adds details throughout, CEO comment) Jan 23 (Reuters) -...

(Adds details throughout, CEO comment)

Jan 23 (Reuters) - Australia's biggest insurer QBE Insurance Group (QBE) said on Tuesday it expected to report a full-year after-tax loss of about A$1.2 billion ($961.80 million), hurt by impairment charges in its North American operations.

The company flagged in a statement that it expected its combined operating ratio (COR), a percentage of claims payouts against premium income, could rise to 104 percent, above the target COR range of 100-102 percent.

The company is due to report its full-year 2017 results on Feb. 26.

The Sydney-based insurer also said it sees COR target range of 95.0 percent to 97.5 percent in 2018 fiscal year.

"This has been a challenging year for QBE, reflecting an unprecedented cost of catastrophes as well as the particularly disappointing deterioration in our emerging markets businesses," said Pat Regan, QBE Group's chief executive.

The insurer said it expected full-year 2017 COR of 109 percent from its North American business and 115 percent from its Asia Pacific business.

QBE said its full-year earnings were affected by an impairment charge of about A$700 million on the reworked assumptions used to calculate the value of North American goodwill and a write-down of A$230 million that takes into account the reduction in U.S. corporate tax rates.

QBE is also conducting a strategic review of its Latin American business in a bid to simplify group operations and reduce risk in a region expected to report a COR of 114 percent in 2017, the company said.

($1 = 1.2477 Australian dollars)