CN Rail sent letters to the City of Thunder Bay and Fort William First Nation on Tuesday saying the rail line is not responsible for replacing the James Street bridge.

The bridge is the most direct link between the First Nation and the city. It has been closed to cars and trucks since a fire last October.

One letter addressed to Thunder Bay mayor Keith Hobbs, from CN's vice-president of law, said the railway is unhappy with how the city has spoken about the bridge repairs in the media, and it does not appreciate the city attacking CN's reputation.

The railway said the bridge is 30 years past its expected life and, while the rail deck is safe for travel, the section for vehicles is not.

The railway interprets its century-old agreement to mean it is responsible for bridge maintenance β€œin perpetuity,” but not its replacement.

The mayor has been threatening to take the company to court, saying that agreement compels CN to pay all costs of making the bridge safe for vehicles.

In the letter to the mayor, CN offered to pay up to 50 per cent, or $1.5 million of the cost to allow vehicles to travel on the rail deck. In doing so, CN said it would then be released from the original agreement.

Other solutions suggested by CN include the railway paying all of the costs to fix the bridge so vehicles can travel on the tracks, and then going to court to determine who is ultimately responsible.

The final offer from the railway includes CN sharing the rail deck with vehicles as long as the bridge can safely accommodate the traffic. The company would then re-negotiate an agreement with the city.

The railway said it can have the bridge open within weeks.

 CN says if there's a lawsuit- any financial contribution to re-open the bridge would be off the table.

The railway has given the city until Tuesday at 5 p.m. to respond. City council is expected to discuss the matter at a Monday night meeting.