An inquiry into the behind schedule, over-budget hydroelectric project at Muskrat Falls will launch this fall, says Newfoundland and Labrador Premier Dwight Ball.

Speaking at a Liberal Party fundraiser on Thursday night in St. John's, Ball said terms of reference are being drafted and he "cannot wait" to launch the inquiry.

"Tory leader after Tory leader jammed this project down our throats," he told the crowd at the $500-a-plate dinner.

"It was not Paul Davis running this province when he was premier. Nalcor was running this province."

The announcement is a reversal of the Liberal party's position.

In June, Ball's Liberal party said an inquiry would distract Nalcor from its main task of getting the hydroelectric project completed as quickly and cheaply as possible.

Critics and supporters have both called on the provincial government to start an inquiry immediately. Opponents say it's important to identify issues with the project as soon as possible.

Muskrat Falls North Dam July 2017

A view of the Muskrat Falls North Dam, as seen in July. The project has ballooned more than $5 billion over the initial budget and has been described as a "boondoggle." (Nalcor)

Despite the Progressive Conservatives sanctioning the controversial project while governing the province, leader Paul Davis says an inquiry would only confirm they acted with the best available information at the time.

The hydro project has ballooned in cost to $12.7 billion, including financing — more than $5 billion higher than the original estimate.

Ball's speech happened in front of about 500 people at the St. John's Convention Centre.