Billy Hayes, CWU general secretary, said: “An increase is always welcome, but this year of all years – when the economic recovery is continuing and there is a general election on the horizon – we expected the government to be bolder in sharing that success with low paid workers who have suffered most under this government.

“The minimum wage remains inadequate for the majority of families to live on, meaning the government is simply subsidising low-paying companies through in-work benefits to make up the shortfall.

“George Osborne has failed to meet his promise of a £7 minimum wage which he made over a year ago. Wages have stagnated for years under the coalition government. They have taken strong action on apprenticeships' pay, but number 11 has missed its opportunity to put low pay for over a million workers right before the election.”

The government has announced that the minimum wage will rise in October by 20p an hour to £6.70 (3 per cent). The hourly rate for 18 to 20-year-olds will go up from £5.13 to £5.30 (3 per cent) and by 8p to £3.87 for 16 and 17-year-olds (a 2 per cent rise).

The statutory minimum for apprentices will increase by 57p to £3.30, an increase of 20 per cent.