Lorne Calvert, seen here in June of 2006, was premier of Saskatchewan in the last NDP administration. (Jeff McIntosh/The Canadian Press)

Saskatchewan politicians continue to spar over the issue of transparency and reporting expense claims for government travel.

Expense claims have been a hot topic ever since the NDP Opposition raised questions about the use of a pricey car service during trips to London, England, by two cabinet ministers. The civil servant who booked the service repaid the expense, just over $7,000, on Monday.

On Wednesday, Cam Broten, leader of the NDP, called for an independent audit of cabinet minister travel and expense claims, arguing that may be the only way to fully understand details of recent trips by government ministers.

Broten noted that when his members try to get answers about trips, the government responds with threats.

"We were told by the government that we needed to stop asking questions of this nature or they were going to bring in former legislators and bring in Betty Calvert into the discussion," Broten said. Calvert is the wife of former NDP premier Lorne Calvert.

The government has pointed out that Lorne Calvert made a trip to Paris in 2006 and added it appeared Calvert and another minister may have done some personal sightseeing on the government tab. However, when the two denied that, the government said it accepts their word on the point.

With files from CBC's Stefani Langenegger