In the first case, the managing director of Home and Industrial Maintenance Services Pte Ltd, Ang Ser Hock, pleaded guilty on Aug 8 to 53 counts of failure to pay salaries totalling $31,268.22 to 53 employees between October 2006 and February 2007.

Another 22 counts were taken into consideration during sentencing.

The workers were owed wages ranging from a few days to six weeks.

Their salary claims were adjudicated by the Labour Court and orders were made for the company to pay the arrears, said the Ministry of Manpower in a statement on Monday. But the orders were not compiled with.

A total of 75 charges were then brought against the company and Ang.

Ang admitted the offences on Aug 8. As he was unable to pay his fine, he has to serve four months in jail.

In the second case, IMM & IMM Cleaning Services Pte Ltd was convicted on Aug 13 on two charges and fined $1,500. Another 12 charges were taken into consideration.

Its managing director, Andrew Sivanesan Balakrishnan, was also fined $1,500.

The firm failed to pay salaries ranging from one to three weeks to 14 cleaners after terminating their contracts.

The salary arrears amounted to $5,573.

MOM has prosecuted four cleaning companies since last year for violation of the Employment Act.

Another five firms will face similar action soon.

Mr Quek Jen Juan, MOM's Senior Assistant Director of Labour Relations and Workplaces Division, said: 'The Ministry is stepping up on our education and enforcement efforts on employment conditions of workers, especially lower salaried workers in sectors such as cleaning. The Ministry has also intensified outreach efforts with partner agencies to raise employers' awareness of their statutory obligations under the employment laws.'