M1 said on Tuesday that some of its customers had been experiencing intermittent service for voice calls and text messaging since 7am.
A spokesman for the telco said that mobile data services are not affected. "We are striving to resolve the issue and sincerely apologise for the inconvenience to our customers," he said in an e-mail to The Straits Times at around 10.30am.
At about 8.20am, M1 informed customers about the disruption in a post on Facebook. The post had attracted over 2,000 comments and was shared more than 1,400 times as of 10.50am.
Netizens said they had trouble with M1's mobile network in various parts of Singapore, including the Central Business District, Bukit Batok, Clementi, Sengkang and Pasir Ris.