The agency in charge of parliamentary staff has agreed to a cash bonus for union members, despite John Key's National Party previously denouncing such deals as discriminatory.

An email obtained by the Herald on Sunday shows union members will receive a one-off, $1000 bonus from the Parliamentary Service - double the amount non-union members will get.

During the Helen Clark Labour administration, union staff once landed an $800 bonus. Act and National blasted the pay-off then, calling it "corrupt" and accusing Labour of cronyism.

That attack was led by National's Don Brash, who accused the Government of a discriminatory breach of employment law.


Twelve years on, Brash said the National-led Government had failed to take a hard line on employment law and unions. "I think it's bizarre it would agree to a deal that clearly incentivises their own staff to belong to a union," he said yesterday.

A Service and Food Workers Union spokesman said unions were rewarded because they invested their own money and time in the latest negotiations. "It pays to participate," he said.

Staff will also receive a pay rise of about 1.5 per cent a year.

"This collective agreement is the first for this group of staff to contain any pay rise at all since the one signed in 2008," a Public Service Association spokesman said.

The Parliamentary Service provides services to MPs and the House of Representatives and runs the parliamentary precinct.