Justin Trudeau said Thursday he "inadvertently" used one of his parliamentary travel points to pay for a trip to a paid speaking engagement in 2012, and later found and repaid two other claims for per diems on days he was on private business.

Trudeau said his agent at the time, Speaker's Spotlight, paid for his travel to Kingston in April, 2012, but that an invoice was inadvertently sent to his MP's office and he was reimbursed for the amount, due to a "human error" by his staff.

All MPs are allowed 64 travel points per year, with one point worth a return trip.

"Shortly after being advised of this error, I wrote a personal cheque for the improper claim of $672 and asked that it be delivered to the Receiver General for Canada immediately," Trudeau wrote in a statement from Thornhill, Ont., where he was speaking with the media Thursday afternoon.

Trudeau added that this event led his office to conduct a review of his expenses and two more improperly billed invoices were discovered.

"One is from Nov. 6, 2009, for $83.55, and the other is from May 7, 2010, for $84.50. While I was travelling on those days, the main activities that I undertook were related to contracts with Speaker’s Spotlight and my return home to Montreal. As such, I have reimbursed the Receiver General $168.05," Trudeau wrote. The two amounts were for per diems — meals and incidentals — that Trudeau had charged.

Liberal Leader Justin Trudeau admitted Thursday he claimed expenses for private speaking engagements, saying the claims were an error and he has repaid them. (Adrain Wylde/Canadian Press)

Speaking to reporters in Thornhill, where he was appearing at an event with the provincial Liberal byelection candidate for the area, Sandra Yeung Racco, Trudeau described the per diems as "perhaps not properly claimed."

He added, "One of the most important things about my approach to politics is about creating a level of honesty, openness and transparency. That means admitting when mistakes were made and taking responsibility for them and fixing them in a manner that will hopefully will continue to restore people's trust in our political system."

NDP Leader Tom Mulcair, speaking to reporters outside the NDP caucus room in the House of Commons, pointed out that in June Trudeau had denied spending parliamentary resources while conducting his speaking engagements.

"Frankly, I think he's stolen a page from Stephen Harper's playbook — deny, deny, deny — until you get caught and then you apologize," Mulcair said.

In his statement, Trudeau said that if the system of proactive disclosure his MPs are now using to publicize their expenses was in force earlier, the "errors" could have been caught sooner.

Trudeau ordered his caucus members, including senators, to post their travel costs for each trip, and any hospitality expenses, starting last fall. So far, expenses have been posted for only the fiscal quarter ending in September 2013.

Conservative MPs adopted a similar system in December, although their postings are more up to date. NDP MPs are not posting their individual travel and hospitality claims.

Last year, after a Saint John-based charity revealed it lost money on an event after paying a $20,000 speaking fee to Trudeau, he offered to pay not only the charity's money back, but any organization he'd billed for speaking appearances since he was first elected.

After the Grace Foundation in Saint John went public about the fact it had paid Trudeau to speak at an event, the House of Commons passed a motion in October that, among other things, asked administrative staff in the House to investigate the use of members' travel points for paid speaking engagements.

In his statement, Trudeau said it was that investigation that led to a letter to his office from the Clerk of the House of Commons, Audrey O'Brien, alerting him about the inappropriate claim for his Kingston speech.