Workers on North America's busiest rail line are on strike, threatening major disruption for hundreds of thousands of passengers travelling across the New York City region ahead of Monday morning's commute.

Unions representing New York's Long Island Rail Road (LIRR) workers launched the strike on Saturday after failing to reach a deal with rail management over pay and work rules.

The walkout entered its second day on Sunday and marks the first strike on the LIRR in over 30 years for around 3,500 union workers, following a two-day stoppage in 1994.

The Metropolitan Transportation Authority (MTA) has warned there is "no substitute" for the railroad, urging commuters to work remotely if possible.

No formal talks between union leaders and management were scheduled for Sunday, raising the prospect that the disruption could continue into the busy weekday rush on Monday.

Limited shuttle services are being provided for stranded passengers, though the MTA has warned of "severe congestion and delays".

Donovan Richards Jr, the Queens borough president, told ABC's local affiliate on Sunday that he did not believe the city was fully prepared for the scale of disruption the LIRR shutdown could cause.

"For working-class people, you can't just say stay home. All of us are not Wall Street bankers," Richards Jr said "We need to be able to ensure that working-class people can make it into the city."

The shutdown is already affecting travel and events across the region. The New York Mets baseball team warned fans attending weekend games at Citi Field in Queens to expect transport difficulties.

A Reddit forum dedicated to discussions about the LIRR has been undated with comments and questions from commuters anxious about how they will get to work or school.

Ramses Brye, a resident of Queens, told the BBC's US partner CBS News that he discovered the strike while travelling to an overnight shift.

"I took the train at midnight. That was the last time, and then I looked at the [TrainTime] app at like 12:30, and, like, yeah, they're definitely on strike," Brye told CBS.

Another commuter from Long Island told CBS News his usual journey into Manhattan had become significantly longer on Saturday, requiring two buses from Port Washington to reach the city.

New York Governor Kathy Hochul has urged the unions and MTA to come to an agreement, warning that an extended shutdown would cause widespread disruption.

The coalition of unions representing LIRR workers says it is seeking improved pay and conditions after years without wage increases.

"To every LIRR passenger whose trip is disrupted, know that the MTA left us no choice but to strike," said Gil Lang, General Chairman of the LIRR General Committee at the Brotherhood of Locomotive Engineers and Trainmen (BLET), one of the unions.

"After three years without raises, we cannot make any more compromises to cover for the MTA's mismanagement," Lang added.

MTA chair and CEO Janno Lieber defended the agency's position, saying it could not "responsibly make a deal that implodes MTA's budget".

"And we refuse to make a deal that puts it on riders and taxpayers to fund outsized wage increases – far beyond what anyone else at the MTA is getting – and for folks who are already the highest-paid railroad workers in the country," Lieber said.