A loose component in the ventilation system brought MTR services on the Tsuen Wan Line between Admiralty and Central to a halt for 30 minutes yesterday, while minor incidents plagued other lines.
The delay came after the faulty part tripped power switches four times between the two stations from 10.50am until noon, the MTR Corporation said.
A platform was closed for inspection without any immediate service disruption as trains were diverted to another platform.
Maintenance workers found the loose part during the check and the MTR Corp halted the service at 2.10pm for repairs.
Passengers on the Tsuen Wan Line had to change trains at Central to reach Admiralty. Normal services resumed at 2.40pm, a spokeswoman said.
The Transport Department said it had asked the MTR Corp to submit reports on the incident.
Meanwhile, two signal failures at Choi Hung in the afternoon also caused minor delays on the Kwun Tong Line.
The spokeswoman said problems occurred at the same position between Choi Hung and Diamond Hill stations twice, at 3.05pm and 5.20pm, slowing down the trains. Services were back to normal more than an hour after the first incident, and 40 minutes after the second.
Signalling systems on the Tung Chung line and Airport Express also experienced problems in the evening, a source said.
However, the MTR Corp said it did not have any record of this.
The incidents heap further embarrassment on the railway company, less than a week after it conceded rail service performance had been "very bad" on the East Rail Line in the first half of the year.
It told reporters last week that the service performance of the system was stable in general.
Lawmaker Gary Fan Kwok-wai, of the NeoDemocrats, called the MTR's performance "ridiculous" and urged the company to start replacing its signalling systems earlier than scheduled.
"It focuses only on public relations, but does not improve its services," he said. "Even one incident in two months is very inconvenient for passengers."
On June 30, a burst water main caused lengthy delays on the East Rail Line.
Under an agreement with the government, the MTR Corp faces a penalty of at least HK$1 million if services are disrupted for more than 30 minutes. It has been fined HK$40.5 million over the past two years.