ZURICH (AFP) - Reinsurance giant Swiss Re estimated Monday that Japan's earthquake and tsunami have cost it some $1.2 billion (847 million euros), but said this figure could be revised upwards.

"Based on preliminary estimates, Swiss Re expects its claims for the earthquake and the tsunami, net of the benefits of retrocession, to be approximately $1.2 billion before tax," the group said in a statement.

"Our claims estimate is subject to a higher than usual degree of uncertainty, and may need to be subsequently adjusted," it warned.

The determination of actual claims would take several months given the widespread destruction from the 9.0 magnitude earthquake and devastating tsunami that struck Japan on March 11, the reinsurer said.

An ensuing nuclear crisis at the Fukushima No. 1 plant is, however, unlikely to lead to significant loss for the insurance industry as coverage for such facilities in Japan excludes earthquake shock, as well as fire following an earthquake and tsunami, Swiss Re said.