About 750,000 women will receive an extra £9 a week in state pension under plans for a new £144-a-week flat-rate payment, the Government will pledge today.
A White Paper will promise to simplify the system and sweep away means-testing such as the pension credit, which tops up the current basic £107-a-week pension.
Women, particularly mothers who take time off work after having children, will be the main winners from the new single-tier pension. At present, 2.8m women receive a state pension of less than £80 a week because they have not built up enough national insurance contributions, compared with 474,000 men.
Ministers say that low earners and the self-employed will also benefit, but people in final-salary pension schemes face a rise in national insurance payments, as they will lose their current rebates.
Iain Duncan Smith, the Work and Pensions Secretary, said: "The single tier will mean that more women can get a full state pension in their own right." But pensioners' groups warned the reform would offer nothing for today's pensioners and prove "a con trick" on younger people.
Dot Gibson, general secretary of the National Pensioners Convention, said: "The worst affected will be around 5m older women who don't have a pension anywhere near £144 a week and would clearly benefit if they were included in the new arrangements, but look like they are going to miss out. This will only add insult to injury to millions who have made a contribution to our society but are still living in poverty."