The Remuneration Authority has given MPs a nearly 2.5 percent pay rise.

The pay rise is backdated to July this year, and takes an ordinary backbench MP's salary to $160,024 - a rise of nearly $4000.

Photo: RNZ / Alexander Robertson

Last year MPs received an increase between 3 and 4 percent after a law change aligning their salaries with public sector pay rises.

Under the current determination, Prime Minister John Key's salary goes up to $459,739, an increase of more than $11,000.

His deputy, Bill English, gets an $8000 pay rise, going to $326,697.

The Opposition leader, Labour's Andrew Little, receives $288,900, going up from $281,881.

MPs have also received a slight increase of 0.4 percent in the tax-free allowance that covers expenses such as sponsorships, passport photos and gifts.