SATS shares fell 2.7% after the airport ground services provider disclosed work pass-related irregularities involving workers employed by some of its contractors, following an internal audit.

The company said it had identified the irregularities during a routine internal audit and had taken immediate action against the companies involved. It has also strengthened internal verification controls to ensure contractor workers are deployed in accordance with the conditions of their respective work passes.

The disclosure came after Singapore's Ministry of Manpower said it was investigating contractors and subcontractors engaged by SATS over alleged work pass offences.

SATS shares had ended unchanged at S$3.66 on Monday, before the company's statement.