Via Rail trains will bypass Toronto's Union Station during part of the G20 summit week in a move that will inconvenience thousands of riders.

A Via Rail train at Union Station, which the national passenger railway service will bypass during the G20 summit. (Mark Blinch/Reuters)

Via trains will not arrive at or depart from Union Station from June 24 to June 27, the rail company said in a release Thursday.

"Due to the proximity of Union Station to the main meeting location, we know that there will be major congestion, making access for our customers very difficult," said Via CEO Marc Laliberté in the release.

"We regret the inconvenience these changes may cause, but we believe that making them well in advance and communicating this information to travellers now will help minimize access issues for our customers and ensure the continuity of our operations.”

Via will instead use its suburban stations in Oakville, Brampton and Oshawa, and the Oriole GO Transit station in north Toronto.

Passengers on trains going through Union will have to disembark at one of the suburban stations and take a shuttle bus to another station to catch a connecting train, Via spokeswoman Catherine Kaloutsky told reporters Friday.

For example, riders hoping to travel from Windsor for Montreal would take the train to Oakville, at which point they would have to get off the train. Via will then shuttle them in a bus to the Oshawa station where they can board a Montreal-bound train.

Via said it will "make every effort" to minimize wait times for shuttle buses, but travellers should expect delays. Authorities have confirmed that there will be a number of traffic restrictions on roadways near the G20 site during the weekend.

The June 26-27 summit will be held at the Metro Toronto Convention Centre, a stone's throw away from Union Station.

About 5,000 people who have already booked their tickets stand to be affected by the changes, Kaloutsky said.

Via also said it will be operating on a weekend schedule from June 24 to June 27 due to "extremely low advance ticket sales."

Service on the suburban GO Transit system — which also uses Union as its major hub — will run as usual during the summit.

Union is Via Rail's busiest hub, with more than 50 per cent of all Via passengers travelling through the station.

Via trains transport more than 11,000 passengers daily around Canada and the company operates 503 intercity, transcontinental and regional trains each week, linking 450 communities across its 12,500-kilometre route network.