SINGAPORE (AP) — A Singapore court sentenced four Chinese immigrant bus drivers on Monday to up to seven weeks in prison for instigating the city-state's first labor strike in 26 years.

Three of the men were sentenced to six weeks' imprisonment. A fourth driver faced an additional charge of publicizing the strike in an online post and received a seven-week jail term for his larger role.

Another driver was jailed for six weeks in December and has been deported.

In the Nov. 26-27 strike, 171 Chinese bus drivers for a public transport company protested over being paid nearly a quarter less than their Malaysian colleagues. The strike disrupted about 5 percent of the country's bus services.

Senior district Judge See Kee Oon said the sentences needed to be long enough "to ensure that others are not emboldened toward attempting similar displays of dissatisfaction over employment terms or conditions."

The government said a police investigation found that the strike was premeditated and that the drivers had been absent from work without reason.

Police are investigating allegations by two of the drivers that officers assaulted them while they were in custody. In an interview with a documentary filmmaker in January, they said they were threatened and beaten by police during questioning.

Walking off the job in protest is almost unheard of in Singapore, which requires essential service workers such as bus drivers to give 14 days' notice of a strike. The last strike was in 1986 by shipyard workers.

Among the 171 Chinese bus drivers who participated in the strike, 29 had their permits revoked and were deported to China, while others were issued warnings and allowed to continue working in Singapore.