Tony Blair on Tuesday night gave his clearest indication yet that Labour will not raise National Insurance contributions to pay for a boost to health spending in the latter half of this decade if it wins Thursday's general election.

As the three main party leaders come to the end of a campaign in which taxation and spending on public services have been central issues, the prime minister said the £8bn annual increase in NI introduced in 2002 “takes care of the catch-up that was needed for the NHS”.