Turkish construction company Gama has described picketing at its sites in Dublin by SIPTU as illegal.
The company said the strike was a pretext to force the company to make unjustified concessions on unsustainable overtime claims in advance of LRC talks on Monday.
Gama said it had been prepared to attend talks at the Labour Relations Commission - provided pickets were lifted and intimidation ceased - but said SIPTU had deliberately breached both conditions.
It described the union's strike ballot as flawed.
SIPTU described the claims as outrageous, and rejected suggestions of illegality and intimidation.
Meanwhile, the Minister for Enterprise Trade and Employment, Micheál Martin, has appealed to striking Gama employees not to go on hunger strike.
Speaking in Dublin, Mr Martin defended the Government's record in relation to the workers, who are from Turkey.
Mr Martin said the Government had succeeded in getting a significant amount of money in basic pay which had been due to the vast majority of workers.
However, he also accepted that issues relating to overtime remained to be addressed.
Mr Martin appealed to the Turkish-based multinational company to get involved in talks at the Labour Relations Commission without pre-conditions.
