Work has been completed on the first four Halifax-class navy frigates to be modernized under a $4.3-billion federal program.

Following recent sea trials, HMCS Fredericton is preparing for a resumption of duty early next year, Defence Minister Rob Nicholson said Monday in Halifax.

The program also saw the modernization of HMCS Halifax, Calgary and Winnipeg. They are currently undergoing trials.

“This comes at a time, I don’t have to tell you, when the demands of the international community are significant and our navy is increasingly needed patrolling our coasts and participating in domestic and international exercises,” said Nicholson.

Work is being done to add radar and command and control systems to the vessels, while upgrading communication technologies and radar and missile capabilities.

“There were roughly 150 different engineering changes that took place within the ship, some of them very small, some of them very large, the largest being the combat management system,” said project manager Geoff Simpson.

“The combat system on board these ships must be able to gather a lot of data analyzing it, respond quickly to enable the crew to be able to operate effectively in this environment,” said Rosemary Chapdelaine, president of Lockheed Martin.

More than 30 companies and hundreds of workers have been involved with the project.

“Our workforce on the FELEX program has reached peaks of 500 employees of the shipyard,” said Irving Shipbuilding president Kevin McCoy. “It’s a significant project for our yard.”

Nicholson said the project is on budget and on time. Eight more Halifax-class navy frigates will be modernized by 2018.

This will be the last major upgrade to the ships, which are expected to last until sometime into the 2030s.

With files from CTV Atlantic's Jacqueline Foster and The Canadian Press