Lloyd’s new exposure arising from the US terrorist attacks of September 11 is about $3.8 billion – equivalent to 12% of the market’s 2001 capacity. Lloyd’s Chairman Sax Riley said the figure will have a significant impact on the market, but said its “strong capital base” will absorb the loss.

“The size of our asset base, the spread of the losses and the resilience of the reinsurance programs in place are important in coming to this conclusion,” he said.

But that show of confidence hasn’t prevented the market upping next year’s premium levy on members from 1.1% to 2%.

The additional income will contribute to Lloyd’s Central Fund, which is expected to boost central assets to $1 billion over the next two years.

Mr Riley said the worldwide surge in premium income means that this is the right time to take steps to build up reserves for the medium to long term. Predicting that the central fund will have more reserves at the end of this year than it did at the end of last year, he said this is “ a prudent and responsible move in the wake of what will be the world’s biggest ever insurance claim”.

“This is an exercise in enhancing the market’s financial viability for the future,” he said. “Increasing the fund does not mean we are expecting syndicates to be unable to meet their liabilities. [It] strikes us as a sensible precaution when facing so many unquantifiable aspects of the tragedy at this time.”

Mr Riley said the long-term impact of the US attacks on the insurance industry is yet to be fully appreciated. “Clearly there will be a contraction of global insurance capacity which will fuel the premium rate rises we’ve been seeing since the last quarter of 2000.”