A Government rethink of the new personal retirement savings accounts (PRSAs) has been urged by the Amalgamated Transport and General Workers' Union.
The union says it is "alarming" that employers will not be obliged to make contributions to PRSAs made available to their employees.
From this autumn, employers which do not provide an occupational pension scheme will be obliged to offer employees access to a standard PRSA. But there will be no incentive for employers to contribute to such schemes, said the ATGWU district secretary, Mr John Bolger.
"This places all the responsibility with the employee and makes a pension more expensive to fund. PRSAs will yield about half the benefits available to an employee compared to a standard occupational scheme."
The union, which claims employers are "increasingly shirking their responsibilities" in relation to pension provision for staff, says there are "real hazards and risks" attached to PRSAs.
"There are no defined benefits for the worker on retirement, while the capital invested in the fund may well decline in value if the market value of the investments chosen by the PRSA provider falls," it says.
Mr Bolger said concerns about the scheme came in addition to a "worrying trend" which had seen employers move away from offering defined benefit schemes, in which workers were assured of a specified pension on retirement.
The Pensions Board, he said, estimated there were still two employees in defined benefit schemes for every one with a defined contribution pension, which offered no guarantee of a specified pension.
The ratio was shifting each year, however, in favour of defined contribution schemes.
"More and more employees are being offered defined contribution schemes, where the investment risk lies solely with the employee.
"As we have seen recently, pensions have been decimated by falling stock markets. The ATGWU demands that this alarming trend be reversed and that workers be given the opportunity to choose from a selection of occupational pension schemes."
Another concern, said the union, was the fact that only about one in four private sector workers were members of an occupational pension scheme. Those in low-paid employment were less likely to have access to a scheme than others.
"Something has to be done," said Mr Bolger.
"In the next 20, 30, 40 years our pensioners will get poorer and poorer because of insufficient pension provision and they will have to work later in life, even past 65 years of age. Dying on the job could well become a reality."
