M1 has partially restored 3G services brought down by an affected mobile network switch.

At around 12am on Wednesday, the telco posted a message on it Facebook page saying restoration work was progressing well with a "significant" number of customers receiving their 3G signals. At about 9am, it said more customers were back online and it was working towards full network restoration.

The problem started at 3am Tuesday when one of its vendors was upgrading transmission equipment at network headquarters and caused a power problem. That set off gas suppression and water sprinkler systems, which tripped one of its mobile network switches, causing the loss of service.

Affected users were mainly in the south-western part of Singapore, including areas like West Coast, Jurong and Tuas. Some customers reported receiving no signal at all, while others said they had intermittent use of their devices.

The telco issued an alert on its website and Facebook page at about 6am. Five hours later, a second post said its engineers were restoring services.