SINGAPORE - The intermittent slowness experienced by the immigration clearance system at the Woodlands and Tuas checkpoints earlier this week was due to a technical glitch rather than a cyber attack, the Immigration and Checkpoints Authority (ICA) has confirmed.

Between 5.40pm on Tuesday (May 16) and Wednesday morning, the system experienced slowness, resulting in a longer processing time and delays at checkpoints.

In a Facebook post at noon on Wednesday, the ICA said that the system had returned to normal at 5.30am that day.

An ICA spokesman said that all available resources were deployed to manage the situation, with both checkpoints running at full capacity on Tuesday.

Officers who were on duty on Tuesday afternoon worked overtime, and night- shift officers were asked to arrive early. Travellers were advised to postpone non-essential travel.

Mr Al Furqan, a 29-year-old property executive, told The Straits Times on Tuesday evening that he was at the checkpoint at 7.30pm on his motorcycle.

"I reached Johor Baru Customs only at 10pm," he said.

Mr Furqan, who shared a photo of motorcycles stuck in a jam at Woodlands Checkpoint at 7.40pm, added that jams usually take about 11/2 hours to clear, but the one on Tuesday took twice as long.