Less than a third of low-earning private sector workers pay into workplace pensions schemes, data from the Office for National Statistics (ONS) has shown.
This figure of 27 per cent among those on weekly salaries between £100 and £200 compares to 81 per cent in the public sector on the same pay range.
Generally, the public sector was more engaged with pension savings, with almost half - 48 per cent - of public sector workers contributing 7 per cent or more.
But in the private sector, the same percentage of workers were contributing 2 per cent or less.
Employer contributions are also significantly different between the two sectors - more than half (58 per cent) of private employers pay up to 4 per cent contributions, while more than 90 per cent of public sector employers pay a contribution rate of 12 per cent or more.
Craig Muir, pensions expert at Royal London, said signing up to a pension in the public sector was the norm, regardless of salary.
He said: "While in the private sector, most wait for the automatic enrolment threshold to kick in.
"These figures act as a stark reminder that we still have a long way to go on the automatic enrolment journey. Clearly more needs to be done to get contribution rates for workers in the private sector up to much more realistic levels."
Auto-enrolment minimum contribution rates will increase next April from the current 2 per cent to 5 per cent, with the employee paying 3 per cent.
One year later, it will increase again to 8 per cent, with the worker paying 5 per cent.
There has been speculation around how people will react to these increases, with research pointing out that some groups are more likely to stop saving into their pension, such as women and millennials.
Overall, the number of workers auto-enrolled into a workplace pension scheme to 73 per cent in 2017, a record high, when compared to 67 per cent in 2016 and 46 per cent in 2012.
Alistair McQueen, head of savings and retirement at Aviva, said there was cause for celebration but also cause for concern, as a record number of employees were saving into a workplace pension but their contributions remained "worryingly low".
He added: "Millennials are leading the way, with their participation growing faster than any other age-group, to match the national average of 73 per cent.
"Participation is rocketing, and this is great. But, unless people make higher contributions, there is a growing risk that the retirement outcomes may disappoint millions of new savers."