The Act Party is keeping up the pressure over youth rates with an open letter urging their reinstatement.

Act MP Sir Roger Douglas submitted a bill last year that would allow the reintroduction of youth rates, which were abolished by the previous Government with some exceptions.

The bill was voted down at its first reading in April, but the Government has in recent weeks left the door open for a return to youth rates.

National plans to campaign on labour law changes ahead of the November election and Prime Minister John Key has not ruled out their reintroduction.

Mr Key last week said he was concerned about high levels of youth unemployment and would be announcing policies to address the issue.

The Act Party is also campaigning on the issue, with its five MPs today putting their signatures to an open letter urging New Zealanders to support the reinstatement of a youth minimum wage.

The letter said there were some 41,400 young people out of work, of which an estimated 12,000 were unemployed as "a direct consequence of the abolition of the youth minimum wage".

It said prospective employers would choose older, more experienced workers rather than taking a punt on a young person who would be paid the same.

"In abolishing the youth wage the Government forced young people to compete with experienced workers, placing youth at a serious disadvantage," the letter said.

"Reinstating the youth wage would allow young people to get a foothold on the job ladder."

The letter said reinstating the youth wage would not shuffle jobs from old to young, but would create more jobs.

Employers who could not afford to take on an extra person on the current minimum wage could decide they were able to afford a less expensive youth worker.

There were 17,726 youths - people aged 18-24 - on an unemployment benefit as of May.