If the Government's National Minimum Wage Commission proposes a basic hourly rate of only £3.50 "there will be the mother and father" of a row, the ICTU's general secretary has warned.
The Irish Congress of Trade Unions is calling for an hourly rate of £5.
Mr Peter Cassells was responding to questions about media reports that £3.50 was the figure the commission would recommend.
Speaking at an ICTU forum on low pay in Dublin yesterday, he said the Government and employers were seriously mistaken if they thought the ICTU was "looking for £5 in order to settle for £3.50".
The ICTU proposes that besides fixing the hourly minimum rate at £5, machinery should be put in place automatically to adjust the rate, in line with average earnings. ICTU assistant general secretary Ms Patricia O'Donovan said strong sanctions should be introduced to enforce compliance.
As part of the enforcement process, unions should be able to take defaulting employers to court and those found guilty should have their names published, she said.
Ms O'Donovan said that in all industrial sectors except one, the average hourly earnings were already above £5 an hour.
In the clothing, leather and footwear sector, average earnings are £4.59, which would mean an increase of just 41p.
The real target of the minimum wage campaign is low-pay sectors such as tourism, many of which are covered by largely ineffective joint labour committees.
SIPTU hotels and catering branch secretary Mr Norman Croke said hourly rates for skilled workers in Dublin were as low as £3.50 an hour, and unskilled workers earned much less.
What worries many employers more than the rate at which a national minimum wage might be set is the prospect of "follow-on" claims from higher-paid employees anxious to protect their earnings differential.
Ms Rhonda Donaghy of Mandate said that in the large retail stores people's pay rates ran from around £3.75 an hour starting off to £5.75 after several years.
While she would welcome increases for people at the bottom of the scale, she said it would take increases of £2.50 an hour or more to maintain differentials for the rest.
And Mr Eamon Waters of the National Youth Council of Ireland said that those campaigning for a decent minimum wage should oppose any attempt to introduce a lower rate for younger workers.
A two-tier system would make the scheme worthless in terms of improving the situation of young people, who tended to be in the most exploited sectors.
A representative of Drogheda Council of Trade Unions, Mr Vincent Lynch, asked what steps would be taken to ensure the minimum wage scheme was extended to people on Community Employment schemes.
He also said that many part-time casual workers such as dockers were excluded from the Family Income Supplement and had to apply for social welfare to supplement low pay. These groups needed special protection.
ICTU's research and information officer, Mr Oliver Donohue, said employers already paying decent wages would welcome a national minimum wage. It would not undermine competitiveness. Some employers, such as small shopkeepers, were paying low wages and charging high prices.
ICTU vice-president Ms Inez McCormack, who is making a submission to the British government's Low Pay Commission in Belfast today, told the forum that setting a decent level for minimum pay was a central element of any plan to redistribute wealth in our society.
In deprived areas of Belfast, 94 per cent of all jobs were in the low-pay sector.