SingTel has yet to fully restore Internet services 27 hours after a fire damaged its key Internet equipment in its Bukit Panjang facility.

It discovered more extensive damage than it had originally assessed, SingTel said Thursday morning. The total number of fibre optic cables damaged was 51 instead of 33.

"More than 100 engineers worked through the night and have restored 33 of the damaged cables," said a SingTel spokesman.

"Our engineers will continue to work hard to restore all services as soon as possible. We apologise to customers who have been affected and thank them for their patience," he said.

About half of the OpenNet's cables at the SingTel building were also damaged.

In a statement sent out close to Wednesday midnight, OpenNet, the builder of Singapore's ultra-fast fibre broadband network, said that some fibre customers in Bukit Batok, Bukit Panjang, Bukit Timah, Choa Chu Kang, Kranji, Marsiling, Teck Whye and Woodlands might have been disrupted.

The fire that started at 2pm at SingTel's Bukit Panjang building brought down banking, telecommunications and even betting services in many parts of Singapore for hours.

SingTel said it disabled its fixed-line voice, Internet, pay-TV and mobile services in the northern part of Singapore, including Choa Chu Kang, Upper Bukit Timah and Woodlands.

Internet links of SingTel's corporate customers including several major banks and telco StarHub were also disrupted.