Unions representing meatworkers, who are poised to go on strike, are worried they may have to sign up to "outrageous working conditions".
They said this could happen if progress was not made in negotiations between the AFFCO freezing works and the Meat Workers Union.
About 1000 meatworkers are set to strike after another breakdown in collective agreement talks between the Talleys-owned company and the union. The two sides have been trying to reach an agreement for almost two years.
Some AFFCO workers, unions said, had signed up to giving the company access to their personal medical records should they try to make a claim against it for accident or illness at work.
Council of Trade Unions (CTU) President Helen Kelly said AFFCO would want workers at all its plants to sign-up to similar conditions.
"What the company is doing is saying, 'We are not going to conclude a collective employment agreement', and the individual agreements are offering all workers around all their plants these conditions.
"So if the workers are not successful in winning a collective employment agreement, they'll find themselves on these agreements."
AFFCO operations director Rowan Ogg said while employees at some of its plants had signed agreements that ban union meetings on site, that had now been dropped and employees had been asked to sign new individual contracts.
It is common practice for companies to ask workers if they have any condition that could affect their work before they start, but Mr Ogg said AFFCO needed deeper access to its workers' health records.
"That helps us to ensure that we don't place people in positions which will, or may, aggravate existing conditions." he said.
He declined to provide examples of situations where not being told about a previous condition had affected an employee's work or safety at the company.
Mr Ogg said if the company read medical records its search would be confined to relevant illnesses or accidents that could affect the person's work.
Mediation breaks down
Court-ordered mediation broke down last week, when AFFCO became the first firm to use a new law which allows employers to walk away from bargaining.
Meat Workers Union national secretary Graham Cooke said the company had been stalling for time until the law came into effect.
"AFFCO's obviously been sitting back there waiting for this legislation to become law and they've embarked upon it," he said.
"As far as we're concerned, we're more than willing to negotiate."
Mr Cooke said the tipping point came last week when AFFCO unexpectedly withdrew seniority provisions which favoured longer-serving workers.
He said 1000 workers across eight North Island sites would strike on Monday and Tuesday.
"Every time we go into negotiations, the company puts new claims on the table which we believe breaches good faith," he said.
"It's like the goal posts continuously move further and further away, so we get no nearer to settling."
Mr Ogg said the claim the company withdrew seniority provisions from bargaining was false.
The union alleged its members had been bullied at work, something Mr Ogg also rejected.
He said the strike was disruptive and unnecessary, and AFFCO had not had the same issues with other unions.
"We've actually renewed agreements with other unions within that time, so it's specific with this particular union," he said.
The union said at least eight bus loads of meat workers would turn up at Parliament to protest about the new employment laws on Tuesday.
Both sides admitted it was up to the Employment Court to resolve the impasse, once the dispute returned there in October.