It says it has reviewed its pension scheme and proposed a range of changes such as raising the age of retirement and increasing employee contributions which could reduce the ongoing cost of the DB pension scheme by around £100m a year.
The changes will reduce pension entitlement for 65,000 members of its final salary scheme that was closed to new joiners in 2001.
It will also mean that the retirement age for scheme members will rise to 65 from 60. In addition future pension entitlement will accumulate at a slower rate and the traditional link between final salaries and pension payments will be broken. Some members will have to pay higher contributions.