SMALL firms and SIPTU, the country's biggest trade. union, clashed yesterday over the cost of introducing an extra week's holidays for workers.

The Irish Small and Medium Enterprises Association (ISME) calculated that introducing the extra week could cost firms £100 million a year. Its introduction will see the statutory minimum number of annual holidays being increased from 15 to 20 days.

SIPTU vice-president Mr Jimmy Somers said he did not accept that the extra week would cost firms that much. All firms had some flexibility and could find ways to introduce it without incurring major costs, he said.

ISME's national director, Mr Frank Mulcahy, said yesterday his organisation was opposed to the extra week's holidays being mandatory and opposed its introduction before 1999.

Officials from the Department of Enterprise and Employment and the trade unions have had discussions on introducing the extra week before 1999, when it is due to come into force under EU law.

Mr Somers said there was no reason why its introduction should be delayed until 1999. He said that phasing it in would make it easier for small firms to adjust.

He said most employees now had collective agreements whereby they enjoyed at least 20 days annual leave and the week would benefit "weaker employees".

He added that the move would bring Ireland into line with most other EU countries.