MONTE CARLO (Reuters) ? There is a gap of billions of dollars between the amount of US catastrophe risk coverage that insurance clients would like to buy and which reinsurers are willing to offer them for next year, according to the chief executive of one of the world?s largest reinsurance brokers.

Insurers are looking for more coverage to protect themselves against a predicted increase in the size and number of major natural disasters, but reinsurers have trimmed their exposures, especially in the southeastern United States, having paid out tens of billions of dollars on storm claims there last year.

?There is a significant gap (of) billions of dollars between what clients would very much like to buy and what is on offer currently,? David Spiller, chief executive officer of Guy Carpenter told Reuters in an interview in Monte Carlo, where the world?s reinsurance industry is meeting.

The event, held in the Mediterranean resort each year, is where insurers kick off renewal talks with their reinsurers on the cost and terms of annual cover contracts for next year.

But the lack of available cover is unlikely to threaten most big US insurers? existence, because they have the financial strength to keep a lot of the risk themselves, Spiller said.

?The shortfall is mainly between what is attainable and what the largest nationwide companies would like to buy. But we have to remember these companies have very big balance sheets and they are not going to buy cover if there?s a very significant margin ... versus retaining it themselves.?

But he said some smaller companies did have an acute need to buy extra catastrophe coverage, to meet regulatory or rating agency requirements.

Reinsurers and brokers are trying to find ways to meet the demand for more coverage, Spiller said.

These include accessing other forms of capital, such as through catastrophe bonds and ?sidecars? ? vehicles set up by reinsurers, backed by hedge funds and private equity to write catastrophe risk. Guy Carpenter is likely to announce shortly a number of deals like this, Spiller said.

But, if reinsurers emerge from this year?s hurricane season without having to pay any costly claims from a storm, then their appetite for taking more catastrophe risk next year may increase, Spiller said. ?My own view is that if we have effectively a loss-free year in 2006 I think more confidence may return (among reinsurers) about whether the risk is manageable or not,? Spiller said.

Spiller, who has been chief of the broker for nine months, having previously worked for rival Benfield, said he saw a number of areas in which Guy Carpenter could expand.

?I see opportunities in continental Europe, I see opportunities in Asia Pacific and I also see opportunities in the US,? he said.

Growth in these regions would come through organic expansion and bolt-on acquisitions rather than a purchase of another big broker, Spillersaid.

?In terms of major acquisitions of companies, I think that?s very difficult. There may be some smaller opportunities.?

But M&A activity would increase in the sector, he added.

?The reinsurance broking market will continue to consolidate. It will be quite difficult to succeed in the global reinsurance market unless you have a certain critical mass in terms of size and infrastructure. The amount of investment we put into assisting our clients is very significant.?