The Montreal, Maine & Atlantic Railway has asked for the Quebec municipality to wait until Tuesday for its response to a legal notice.
It has already missed last week's deadline, and the municipality has said it's now speaking with lawyers to evaluate a possible lawsuit.
At issue is the estimated $4 million cost to clean up the crash site - which is now being shouldered by authorities within Quebec.
MMA is accused of shirking its duty to pay workers to clean up the site and has received a lawyers' letter hinting at a lawsuit.
That dispute is one of several weighing on the U.S.-based company, which is now the focus of different attempts at class-action suits and also a police investigation into the July 6 derailment and fire that killed 47 people.
The company had failed to respond in time to the letter over cleanup costs but it has indicated plans to respond by Tuesday, said Karine Dube, spokeswoman for Lac-Megantic Mayor Colette Roy-Laroche.
She insisted the legal deadline has come and gone – regardless of whether the company replies now.
“We maintain, however, that there was no response to the (legal) notice,” Dube said in a phone interview.
Lac-Megantic's mayor announced last week that a letter was sent to MMA, demanding that it immediately reimburse the town for environmental cleanup costs.
A railway official, Yves Bourdon, has since told The Canadian Press that the company had planned to discuss the issue last Friday.
Fear the company wouldn't pay cleanup costs prompted work crews to threaten to walk off the job.
However, the municipality and provincial government ensured that workers got paid. They are now seeking a refund from the railway.
Bourdon agreed that the municipality shouldn’t have to foot the bill. When asked Friday whether it was normal that Lac-Megantic should have to pay, the MMA board member replied: “It should be our insurance.”
Thousands of residents joined Prime Minister Stephen Harper, Gov. Gen. David Johnston and other political leaders on Saturday for a memorial service for the people who died in the disaster.
Quebec and the federal government have both promised $60 million for emergency assistance and longer-term reconstruction help for the town.
with files from Andy Blatchford