Hundreds of flights from US East Coast airports have been cancelled or delayed due to a telecommunications line outage caused by a construction mistake, US officials said.

Transportation Secretary Sean Duffy said on X on Monday that around 1900 GMT, flights were resuming at LaGuardia Airport and Philadelphia, while flights into Newark and JFK Airports were paused.

"An Amtrak construction crew accidentally cut into a fibre line in New Jersey, which caused a telecom outage and forced the FAA to pause flights in the Northeast," Duffy said.

"This incident underscores the need for additional funding to modernise ageing infrastructure and prevent disruptions like this in the future."

Amtrak is the US passenger train company.

Massive rupture

Around 1900 GMT, Newark Airport, a key New York City-area hub, had 168 flights cancelled and 97 delayed, while Philadelphia had 63 cancelled flights and 189 delays, according to FlightAware.

Monday's airport disruption stemmed from two problems, according to Bryan Bedford, head of the Federal Aviation Administration.

After identifying an outage in the primary telecom line, "we discovered that the backup fibre had a break," Bedford said following a briefing to reporters on new air traffic technologies.

Bedford described the rupture on the backup line as "massive" due to the construction mistake.

He said he expected the primary system to be restored by early afternoon but estimated that repairing the backup line would need 13 hours.