NEW YORK (AFP) - A minor derailment on New York's beleaguered subway system forced the evacuation on Friday (July 21) of 135 passengers to a nearby Brooklyn station, causing delays, suspensions and compounding customer misery, officials said.

One car came off the tracks shortly before 9am (9pm Singapore time) near Brighton Beach, where a replacement bus service was laid on for affected passengers, said the Metropolitan Transport Authority.

There were no injuries in the incident, which came as commuters battle a "summer of hell" owing to emergency repair work on mainline rail tracks at Penn Station, North America's busiest rail hub.

New York's 113-year-old subway system, used by six million people a day, suffers from decades of underinvestment and deferred maintenance, blamed for chronic delays, power cuts and overcrowding.

"Obviously, we're sorry that this occurred this morning," MTA interim executive director Ronnie Hakim said Friday.

Thirty-six people were left with minor injuries in June when two subway cars careened off the tracks, leaving hundreds of people stuck for more than an hour.