Unions and local authority leaders have reacted angrily after it emerged many council workers will lose their right to retire on a work pension at 60.
Unions have insisted the status quo should remain
The decision was revealed in a parliamentary answer by Tom McCabe, the local government minister.
The Scottish Executive said the rules must change to conform to European laws on age discrimination.
However other public workers in Scotland, like nurses and teachers, will not be affected.
The so-called "rule of 85" allows council employees to retire early on a work pension from 60 onwards if their age and years of service add up to at least 85.
Currently about 200,000 council workers are entitled to apply for early retirement through the scheme.
Any change would create a discrepancy between local authority employees and others in the public sector who would still be able to apply for early retirement on a work pension at 60.
Mr McCabe confirmed that rule 85 will be abolished as it falls foul of European age discrimination laws.
But the manner of his confirmation has also caused concern as it was released in a written parliamentary answer.
Joe Di Paola, from the public services union Unison, said he was "upset and concerned" by the issue.
He added that industrial action was a possibility.
Speaking to BBC Radio's Good Morning Scotland programme, he said: "We've been asking ministers over a number of months about their position on the matter and for it to be slipped out in a written answer is really quite reprehensible."
He added: "We are continuing to lobby our MPs to get these proposed regulations changed and are making sure that our members are ready to take action should it require that."
Pat Watters, from local authority organisation Cosla, said as far as he had been aware, discussions with the executive on whether rule 85 would go were still ongoing.
He said: "A group was set up last year with the executive and the trade unions to discuss this. That group met in November and in December to discuss this, with the third meeting actually today.
"I think it is ridiculous for this to happen when we are in the middle of discussions on what we consider to be a serious issue.
"It is our job to ensure that not only people today can get their pensions, but people in the future can get their pensions - that is the reason for these discussions.
"For it to be just dropped in while we are in the middle of discussions, that part of what we have been discussing is now not on the table anymore, I think is ridiculous."
John Swinney said workers face the risk of pensioner poverty
Mr McCabe said he had no choice but to change the rules.
He insisted that ministers were acting in line with "very firm" legal advice that the rule could be in breach of European equality legislation.
"If people feel the advice we have got is wrong, they have ample opportunity to challenge that advice."
He added: "Ministers are acting on this particular issue on the basis of very firm legal advice that we would be in contradiction of our obligations under European law if we don't act."
Scottish National Party finance spokesman John Swinney MSP said: "The government is short-changing local government employees and will be causing enormous concern to workers who have just had their pension rights slashed by this Lib/Lab executive.
"Workers are being badly let down by this government and I urge the executive to reconsider its decision.
"At the very least, the executive must put in place effective transitional arrangements to ensure workers are not subjected to pensioner poverty."
Scottish Socialist Party MSP Carolyn Leckie warned of "dire consequences" if the executive pressed ahead with scrapping the rule.
She said: "The unions and employers were in the middle of discussions over this issue but the executive has unilaterally announced that they will deprive public sector workers of pension entitlements that other workers retain.
"The only message that the Scottish Executive will understand is that of industrial action and I'm sure that thousands of angry public sector workers will be considering exactly that."