Increasing the number of statutory holidays to 17 would be expensive and could exacerbate labour shortages, employers claim.
Employers say they would either have to pay staff extra to work the holidays, or employ more staff to cover the absences - and that could be a problem in sectors such as tourism and retail that they say are already experiencing labour shortages.
All of the city's 3.7 million workers receive 12 statutory holidays. A further five "public" or "bank" holidays, including Buddha's birthday, are left to employers' discretion, though these are usually granted to office workers and other white-collar staff.
Unionists are campaigning for these extra five holidays to become statutory. They argue that almost two million mainly blue collar workers who are not granted these extra holidays are being discriminated against.
Federation of Hong Kong Industries chairman Stanley Lau Chin-ho said yesterday that granting the extra holidays would be too expensive for employers.
"There is a labour shortage for tourism, retail and hotel industries. If existing staff are given more holidays, where can we find the people to fill their shifts?" Lau asked on a Commercial Radio programme.
Lau did not put a figure on the cost, saying a detailed analysis was needed.
But unionist lawmaker Lee Cheuk-yan said that by discriminating against blue-collar workers, employers were making the labour shortage worse by dissuading people from taking up such work. He reasoned that based on two million people earning an average of HK$555.50 a day the annual cost to employers would be HK$5.55 billion - less than one per cent of the HK$1 trillion total wage bill in 2012.
The results of a government study into how many workers receive the five holidays will be released at the end of the year.