Several websites belonging to ministries and government agencies here were offline for some time earlier on Saturday. But the Infocomm Development Authority of Singapore (IDA) said it was due to a "planned maintenance" that took longer than expected due to technical difficulties.

The IDA posted a message about the maintenace on its Facebook page just after 4pm and followed up with a statement to the media saying that such "maintenance are usually undertaken during the weekends and public holidays due to low expected website traffic. The maintenance took longer than expected, due to technical difficulties".

"Maintenance of the websites is progressively being completed. We apologise for the inconvenience caused," said the IDA.

Wesbites of the ministries of Home Affairs, Foreign Affairs, Trade and Industry, Finance and Transport; agencies such as the Singapore Police Force and the IDA were still down as of 5.20pm but a few returned online progressively. Other sites belonging to the Central Provident Fund, Inland Revenue Authority of Singapore, the Ministry of Education and Ministry of Defence, however, remain accessible.

The incident comes a day after the police said it was investigating another cyber intrusion based on a report made by The Straits Times after part of its website was hacked into early Friday morning by a person who identified himself as 'The Messiah'. This is the fourth time that the culprit, who claims to be part of the global hacker group Anonymous, has attacked local websites since September.