Singapore's labour crunch is getting worse and more firms are having difficulties hiring, according to a globalhuman resources firm.

Forty seven per cent of the 647 companies surveyed by ManpowerGroup this year struggled to fill jobs, up from 37 per cent last year.

Blue-collar jobs such as labouring were the hardest to fill along with professional, managerial and executive positions in fields including engineering and teaching.

Companies gave The Straits Times varying reasons for their hiring woes.

Seng Heng Engineering was unable to find an IT specialist to run its computer operations for six months.

"The applicants either have the knowledge but no attitude, or have the attitude but no knowledge," said its human resources and administration executive Violet Ong.

Offering high pay does not necessarily attract Singaporean workers either, said some firms.

Lewe Engineering in MacPherson is willing to pay around $3,000 a month for a mechanical and electrical engineer with three years' experience, but there have been no Singaporean takers.

Some jobs have an image problem, adding to firms' difficulties.

Scrap metal firm Kim Hock Corporation advertised for a site supervisor post paying up to $3,000 a month. Eight weeks later, it remains vacant.

"We have employed some in the past, who simply stopped showing up after one or two weeks, said company executive Tan Suat Hui. "They disappeared and were uncontactable."

Although firms face hiring woes, labour MP Patrick Tay said vacancies in professional jobs are opportunities for Singaporeans. While younger workers may prefer to work in banking and finance, they ought to consider opportunities in growing sectors like health care and construction, he added.

Experts say the labour crunch will force firms to rethink their hiring strategies. ManpowerGroup's Singapore manager, Ms Linda Teo, said companies have "to do more with less", including retraining and retaining their existing workers.

Mr Martin Gabriel, a senior consultant with human resources firm HRmatters21, thinks companies may even have to tailor positions to workers' expectations, instead of having a standard job requirement template.

The hiring crunch could cause some businesses to close, warned Mr Chan Chong Beng, president of the Association of Small and Medium Enterprises. "In the current labour market, it is the workers who put their companies on probation, not the other way around," he said with a sigh.