Zurich Insurance warned today that it expects to report an estimated $100m fourth-quarter operating loss for its main general insurance business, the latest blow for the troubled Swiss insurer as it seeks a new CEO. 

The anticipated loss in the general insurance business stems largely from the aggregate hit of around $275m from storms in Britain and Ireland dubbed Desmond, Eva and Frank late last year. 

The final costs remain uncertain, Zurich said. 

"While the 2015 results for general insurance are disappointing, operating performance for both farmers and global life should be in line with expectations, and the group's capital position remains very strong across all key metrics," Zurich said in a statement. 

Zurich had previously announced a turnaround plan for general insurance, its biggest source of revenue, which included modest job cuts as part of a wider cost-cutting drive. 

It now hopes to exceed its $300m savings target for 2016, the company said.

This should result in charges of around $475m in the fourth quarter, primarily from general insurance, it added. 

The profit warning follows a similar statement in September when large losses stemming from explosions at the Chinese port of Tianjin prompted it to abandon a proposed £5.6 billion bid for UK insurer RSA. 

Zurich's chief executive Martin Senn suddenly quit last month after coming under pressure following a botched takeover bid and a stuttering performance in general insurance. 

Zurich has yet to appoint a successor. There has been media speculation that Generali chief Mario Greco is the preferred candidate.