The representative body for most UK unions, the TUC, said it believes the present level does not do enough to tackle "in-work poverty."

Although its introduction was a long held goal of the unions in the UK, there is disappointment that its effect in raising wages has been limited.

TUC: lower rate for young workers unfair

They have also seen unemployment in the UK continue to fall, despite fears from opponents that a minimum wage might cost thousands of jobs.

The TUC's general council said in a statement that it believes a higher rate could be sustained without significant job losses.

"The successful introduction of the national minimum wage opens the way for a significant uprating in the near future and regular uprating thereafter," said the statement, which will be presented to the TUC Congress in Brighton later this month.

The general council also complained that there was "no justification" for the lower rate of £3 an hour for younger workers.

"It is discriminatory and undermines the principle of establishing fair rates of pay for a job."