'Our salary is simply too low,' said workers' representative Mok Yun-chuen. 'We will fight until the company answers our [demands]. We just want to be treated fairly.'

The 70 workers, who represent about 80 per cent of the company's frontline employees, are paid HK$7,000 a month. Mok said that at similar companies, the average salary was HK$8,500.

Workers said the firm, which covers about 10 per cent of the city's lift maintenance work, was short of staff.

'Many of us are required to work overtime regularly,' Mok said. 'We have to carry out most of the work alone, while under standard procedures two workers should be deployed.'

No agreement had been reached after two hours of talks between management and workers.

Workers were still willing to perform emergency repair work yesterday, but said they would refuse today.

'We will not help in any lift-trapping incidents,' Mok said.

The secretary of Hong Kong General Union of Lift and Escalator Employees, Tsang Chi-kong, said the salaries of lift repair workers were low, compared to other industries.

The company issued a statement last night, urging staff to resume work and treat the safety of the public as their first priority.

It promised to review their salaries according to workers' qualifications next year.

The Labour Department and the Electrical and Mechanical Services Department said they were worried and asked both sides to reach an agreement soon.It was not the first time that workers at the company have taken industrial action. In October 2008 about 60 workers from ThyssenKrupp went on strike in Hung Hom to demand more staff and higher pay.

The firm was fined HK$5,000 in 2009 after admitting that it failed to carry out repairs to a lift that plummeted 14 floors. No one was hurt when the empty lift plunged in Shin Nga House on Fu Shin Estate in Tai Po in October 2008.