A big union wants workers to be paid more if statutory holidays fall on a weekend.

This year, both Anzac and Waitangi Day fell on weekends, meaning workers missed out on penal rates and an extra day off work because those two statutory holidays aren't "Mondayised" as all others are.

Next year, Waitangi Day again falls on a weekend and Anzac Day and Easter Monday both fall on Monday, April 25, meaning workers will have to celebrate those two public holidays on just one day.

The Engineering, Printing and Manufacturing Union says the way the holidays fall is unfair to workers and it will try to address that when it starts negotiating the Metal and Manufacturing Industry agreement next week.

This covers up to 200 companies and is used as a benchmark in other sector negotiations.

"That is one of our key claims to address that unfairness - it's just illogical," said union assistant secretary Bill Newson.

"Our view is very much that annual leave and public holidays all make up the overall leave provision and it just seems illogical to us that nine of the public holidays can be Mondayised, so that they are actually observed, and you get these other two that just slide all over the place."

Mr Newson said there was no argument about the sanctity of Waitangi Day or Anzac Day, but the union would like workers to be able to take all of the public holidays they were entitled to.

The Returned and Services Association has always opposed transferring to a Monday the observance of holidays such as Anzac Day that fall on a weekend, saying that to do so would miss the point of the day.

Chief executive Stephen Clarke said the national executive discussed the issue again this week after receiving a letter suggesting NZ should Mondayise Anzac Day, as some Australian states do.

However, the executive voted for the status quo.

"It's about commemorating the date as it has been since the first anniversary in 1916," Dr Clarke said.

"I think it's about continuing that tradition of commemorating the date of the 25th of April.

"It's a holiday but it is a special day and with the increase in numbers of attendances [at Anzac Day services], we really think the public feels that way too."

Dr Clarke said next year's clash with Easter Monday was unusual and would be a good test of people's commitment to remembering the special day.

He added it might be an opportunity for some people to attend a service in a different location while they were away from home for the long weekend.

A Labour Department spokesman said any plans to Mondayise Anzac Day would require a law change.