The full list of non-ministerial MP expenses was released on Thursday morning, showing MPs spent $2.1m on travel and accommodation over three months.

This features National Leader Simon Bridges' big $114k spend on flights, hotels, and a crown limo, leaked earlier this week.

The MP expenses are usually released alongside Ministerial Expenses, allowing reporters to compare what regular members and high-flying members of the executive spend.

But due to the leak of Bridges' expenses on Monday to Newshub, Parliamentary Services released the MP expenses for April to June alone on Thursday, meaning it's not clear yet what Prime Minister Jacinda Ardern and other ministers spent over the three-month period.

It’s a pretty good Thursday when you get to pop over to the Wairarapa and get a lift in @Kieran_McAnulty’s ute. pic.twitter.com/uGJcCBYF4X — New Zealand Labour (@nzlabour) August 15, 2018

Ardern seemed keen to play up the differences on Thursday, driving around the Wairarapa in Labour MP Kieran McAnulty's ute.

Speaker Trevor Mallard announced that a QC would investigate the leak of Bridges' expenses early on Wednesday.

ALEX LIU/STUFF The Beehive and the statue of Richard John Seddon in Wellington.

Bridges' spending was well over double the next highest spender: National MP for Clutha Southland Hamish Walker, who spent $39,387.

Walker's high spend is unsurprising given he is the MP of the largest general electorate in the country, which requires a lot of driving to get around. Next up behind him is NZ First's Mark Patterson, who is based in the same electorate. A spokesman for Patterson said the high amount was a result of a back payment as a previous allowance had been unclaimed.

As usual, other MPs in large electorates like Waitaki and the East Coast were all among the highest spenders. These MPs would not have access to a crown car like Bridges or ministers, but could use the money on fuel and cabs.

The total spend for the three-month period was $2,110,474, up from $1,493,715 in January-March.

But the early months are a quieter time in politics - during the same April-June period last year MPs spent a closer amount: $1,924,933.

National, as the largest party and the only party with no ministers other than ACT, naturally spent the most: $1,410,659.

Labour was next up with $494,690. Their highest spending MP was Kiri Allan, who is based in the East Coast, and spent $31,303.

NZ First MPs spent $103,613, while the Greens spent $80,871. Both parties have four MPs who are neither ministers nor parliamentary under-secretaries.