SINGAPORE'S Land Transport Authority (LTA) issued a clipped but blunt statement on Tuesday evening, referring to the recent spate of train disruptions as "unacceptable".

"Today's disruptions on the Circle and East-West Lines are the latest in a recent spate of incidents on the SMRT rail network. Commuters have been severely inconvenienced again," said an LTA spokesman.

The LTA said that it has directed SMRT to investigate the various disruptions and give a full account of them while it was also conducting independent investigations.

"LTA will be working with SMRT on the immediate remedial actions. We expect the SMRT board and management team to put in maximum effort and resources," it said, adding that it plans to review again SMRT's management of resources and processes for the maintenance of the rail system.