Singapore Tuesday issued a warning to mainland Chinese bus drivers, who are staging the first strike in the city-state for more than 25 years, an act that could land them in prison.
A total of 102 Chinese drivers working for state-linked transport firm SMRT began their wildcat strike over pay on Monday, refusing to board a shuttle bus from their dormitory to a nearby depot.
An agreement was hammered out to convince them to return to work, but SMRT said more than 60 drivers still did not turn up for duty on Tuesday.
Strikes and other forms of industrial action are extremely rare in Singapore, where the labour movement works closely with the government and private business, making the port city an attractive place for foreign investment.
The last illegal strike was in 1980 and involved the Singapore Airlines pilot's union, the manpower ministry said, while the last legal strike was in 1986.
"Taking the law into your own hands is wrong. This illegal strike is not acceptable and would be dealt with in accordance to the law," Manpower Minister Tan Chuan-Jin told reporters.
"By taking matters into their own hands, the drivers have clearly crossed the line," he said, adding they have "disrupted public transport services and Singapore's industrial harmony".
He said strikes are illegal for workers in "essential services" such as transport unless they give 14-day notice of their intent and comply with other requirements.
The penalty for staging an illegal strike is a fine of up to Sg$2,000 ($1,636), or a maximum prison term of one year, or both.
While the drivers have their grievances, they should have resorted to legal ways to have their complaints heard, Tan said.
"The government views these disruptions very seriously. We have zero tolerance for such unlawful action."
One of the Chinese drivers told reporters on Monday he and his colleagues -- who are not union members -- felt aggrieved over a disparity in pay between Chinese and Malaysian bus drivers.
Singapore has been hiring bus drivers from China and Malaysia because of a chronic shortage of manpower.
SMRT is 54 percent owned by state investment firm Temasek Holdings.