Justin Trudeau sent the letter to Premier Paul Davis days before Christmas.
In it, Trudeau outlined that while the Liberal party supports free trade with the European Union, the terms of the agreement are not working out as planned for people of Newfoundland and Labrador.
"The Harper Government negotiated the deal without proper public debate," he wrote.
"As a result, the government had failed to adequately address the concerns of Canadian sectors that may be negatively impacted by CETA, including Newfoundland and Labrador's fish processors."
Trudeau said the province's support of the CETA agreement was conditional, and hinged on a $400 million transitional fund that would help the industry adjust if minimum processing requirements were abolished.
The Fisheries Investment Fund was created to boost the Newfoundland and Labrador fishing industry
Paul Davis had previously said the federal government is not living up their promises regarding the fund.- Ottawa putting new stipulations on CETA deal, Paul Davis says
In the letter, Trudeau stated, "That promise should be honoured."
Trudeau says it's an issue that MP Yvonne Jones will be chasing when the House of Commons reopens near the end of the month.- See the full letter below: