UK final salary pension funds will be comforted after the market to insure against the cost of longer lifespans has racked up a staggering £8.9bn in deals this year.

The so-called "longevity swap" deals enable employers to cap the risk that their defined benefit pension scheme members will live longer than expected.

The market for these swaps, which launched five years ago, has shown strong growth and it is expected to attract global businesses as workers across the world live longer than expected.

According to Reuters, the pension industry suggests that the longevity market could be very lucrative and could be worth between £9.1tn ($15tn, €10.8tn) and £15.1tn.

The market, for instance, set its record for risks hived off by schemes this year with its biggest deal to date, of £3.2bn from BAE Systems, along with others from AstraZeneca, Bentley and Carillion.

The news agency said life expectancy has been consistently underestimated by statisticians.

To avoid the risk of being forced to pay out money for longer than expected, many schemes are seeking to farm out longevity risk.

But the complex deals can take years to come to fruition.

The device is an alternative to the buyout market.