MTR says what its staff believed to be a "technical glitch" detected on a East Rail train on Tuesday morning rush hour turned out to be a false alarm.

The rail firm said the train was about to turn around in Admiralty and head to Sheung Shui when the incident occurred, causing services to be disrupted for more than half an hour.

Jacob Kam, the firm's chief executive, said the train in question was found to be operating normally after an inspection.

"A monitoring device on the train was wrongly triggered, it was a false alarm," he told reporters before the company's annual general meeting.

"As we all know, there will be some teething problems when new services are put into operation. But of course, we will review how the whole situation was handled in order to make improvement," he continued.

When asked if the rail firm will consider scrapping the first class carriage on the East Rail Line to carry more passengers, the chief executive said there's a long history of the special carriage and it's been popular with passengers.

He said there's a "strong demand" for first class carriage after it was extended across the harbour, adding that current services can meet passengers' need.

The MTR has reduced the number of carriages of East Rail Line train from 12 to nine after it was extended to Admiralty, though officials say a new signalling system can increase train frequency to make up for the reduced capacity.