Loss estimates

ACE and XL Capital: $1bn-1.1bn AIG: $500m Allianz: $930m AXA: $300m-400m Berkshire Hathaway: $2.2bn Chubb: $500m-600m CNA Financial: $200m-350m Employers' Re: $600m GE: $600m Hannover Re: $365m Munich Re: $1.95bn Partner Re: $350m-400m Royal & Sun Alliance: $220m Scor: $150m-200m Swiss Re: $1.25bn Zurich Financial: $700m-900m

The firm now says its exposure could be $700m-900m (�472m-607m), up from its first estimate of $400m.

If the figure proves correct, it will be the highest payout in Zurich's 130-year history.

Zurich said it was "no longer feasible" to expect profits to hit its target of $1.8-2bn this year, causing its shares to tumble by as much as 14% on Monday.

The firm was keen to put the loss in perspective, however, pointing out that even the highest figure only represented less than 2% of its annual premium revenue.

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Zurich is the latest major insurer sharply to hike its assessment of the financial fall-out from the attacks.

Lloyd's faces losses of at least �1.3bn

One firm, US reinsurer Berkshire Hathaway, now says it expects a loss of $2.2bn - the biggest liability figure announced by an insurer so far.

Munich Re and Swiss Re - the world's two largest reinsurance companies - have doubled their estimates to $3.2bn.

German insurance giant Allianz has said it faces claims of $930m, compared with an earlier forecast of $640m.

Lloyd's of London, the main insurance market, calculates its total losses at as high as �1.3bn.

Already, liabilities amounting to more than $13bn have been admitted by insurers.

Analysts now say that the overall bill could exceed the $20bn initially predicted - with estimates for overall liabilities currently ranging from $30bn to more than $50bn.