More than 10,000 users of Netvigator, PCCW's internet service provider, were denied access to the web yesterday when road construction workers accidentally cut three fibre optic cables in Causeway Bay.
The underground cables were damaged by a roadwork contractor for the Highways Department during work on the Central-Wan Chai Bypass, PCCW said.
Most of the affected users were on Hong Kong Island, a spokesman for communications watchdog said, as the cables were located near the Police Officers' Club, which is next to the entrance of the Cross-Harbour Tunnel.
The disruption prompted complaints from users on Facebook and online discussion forums. A person wrote: 'Why did it have to fail just before a Friday night?'
PCCW's network control centre first detected problems with the cables at about 4pm.
It sent engineers to the site and conducted emergency repair work while diverting internet traffic, a spokeswoman said.
Shortly after 7pm, much of the commercial and residential broadband services had resumed, she said.
Hong Kong Telecommunications, a listed unit of PCCW, said it would take action against the contractor, China State Construction Engineering.
The Office of Communications Authority (Ofca) received 16 complaints and enquiries about the internet disruption. PCCW must submit a preliminary report in three days and a detailed investigation report in two weeks.According to Ofca requirements, internet service providers should alert it about any incident that affects more than 10,000 users for longer than 45 minutes. PCCW alerted Ofca within an hour.
Charles Mok, founding chairman of the Internet Society Hong Kong, said the impact on internet access was small.
Only people using landlines to surf the web would be affected, not those on wireless networks, he said.
Data transmission for affected users would slow despite the diversion of web traffic, Mok said. 'This is similar to cars. Even if they are diverted [after an accident], there may still be a traffic jam.'
The Netvigator incident was the second involving telecoms operators in a week.
On Monday, thousands of SmarTone mobile phone users were cut off or experienced problems with phone and internet connections.
In a preliminary report, SmarTone said the breakdown was caused by a backup power generator in Sha Tin which restarted itself repeatedly within a minute.
The 21/2-hour power failure affected a quarter of its mobile network coverage, the firm said. It did not reveal the total number of affected users. SmarTone was also criticised for its delay in notifying customers.