Some Singtel users had trouble connecting to the Internet early yesterday as planned maintenance works took longer than expected, the telco said.

"Due to planned maintenance of our servers, some of our customers may have had difficulty accessing the Internet between 2.15am and 2.55am earlier this morning," a Singtel spokesman told The Sunday Times.

"We apologise for the maintenance taking longer than the typical 15 minutes," she said.

Singtel plans its maintenance at such hours as "there are fewer users on the network and a smaller number of users will be impacted". "All services have since been back to normal," she said.

Several users took to social media to demand an explanation. Facebook user Dean Kng wrote: "In this incident, the least you can do is to keep your customers informed. Such corrective controls should be part of your response and recovery plan."

Facebook user Angie Seow wrote on Singtel's Facebook page at 2.20am saying both her broadband and 4G Internet were down.

She did not try connecting to the Internet after 3am, but could use the Internet at 10am when she woke up.

Singtel did not issue a note on its website or social media platforms.

At noon, it explained what happened and apologised on its Facebook page.

In response to queries, Singtel thanked its customers for their patience and apologised again for the inconvenience caused.

The telco did not comment on whether the outage was islandwide and how many users were affected.