An issue during the production of The Sunday Times caused its printing to be delayed, with the newspaper reaching some households several hours later than usual yesterday.
"We are very sorry for the inconvenience caused to our readers," said Ms Sumiko Tan, acting editor of The Sunday Times and The Straits Times.
All Sunday Times reports on the paper's website and app edition were put outside the paywall so that readers would have easier access to them.
About half an hour before the paper was sent for printing at 1am yesterday, some production systems went down.
Investigations found a storage system problem, which necessitated a reboot of all the affected servers.
This meant that the paper started printing much later, at about 5am.
Meanwhile, the Singapore Press Holdings (SPH) circulation department alerted vendors that the paper would be late and put in additional measures to ensure that it could be delivered as soon as possible to subscribers and news-stands.
Printing was completed by 6.15am. While some copies went to households before 7am, others were delayed because of issues like vendors having to change drop-off delivery points.
Besides The Sunday Times, some subscribers to SPH's other publications such as Lianhe Zaobao, Tamil Murasu and Berita Minggu got their newspapers late.
Mr Chua Wee Phong, SPH's executive vice-president of circulation, said 95 per cent of subscribers got their copies by noon.
Although all the circulation hotlines were activated, staff were not able to answer all complaints.
"We apologise for the delivery delay and for not being able to take all the calls that came in," he said.
The system has since been fixed.