SINGAPORE has deported 29 mainland Chinese bus drivers involved in the city-state's first industrial strike in 26 years.

The drivers, working for state-linked transport operator SMRT, staged the strike on Monday and Tuesday over a salary dispute and to demand better working conditions.

Their work permits had been revoked ahead of their deportation.

"The Ministry of Home Affairs confirms that all 29 former SMRT bus drivers have been repatriated to their home country," the ministry said in a statement on Sunday.

"They were co-operative and the process took place without incident," it said, adding that Chinese embassy officials and SMRT staff assisted in the repatriation.

Four other drivers were charged in court and authorities will lodge charges against a fifth one on Monday for their involvement in the work stoppage that was ruled as illegal by the government.

The strike, the first since 1986 which caught the government by surprise, has highlighted tightly-controlled Singapore's heavy dependency on migrant labour to drive its economic growth amid a labour shortage resulting from falling birth rates.