Responding to queries from The Sunday Times, a Mindef spokesman on Sunday said that students and staff from Temasek Polytechnic visited Pasir Laba Camp in Jurong last Tuesday for a National Education visit.

'Two pen flares, used in the hands-on segment, were discovered missing during the visit. Mindef is investigating the incident,' she said.

A pen flare is a small, hand-held device that fires a flare. Flares are used to signal a person's location or to illuminate an area.

While often used as safety devices, pen flares have been the cause of several accidents abroad.

Read the full story in tomorrow's edition of The Sunday Times.