A survey of 2,000 workers found that those on part-time contracts believed their employers were not able to offer them longer hours.
A separate study of 1,000 employers found that a third had reduced hours for some of their staff during the past five years.
The Chartered Institute of Personnel and Development (CIPD) said its research suggested that employment will continue to increase in the first quarter of the year thanks to growth in private firms.
The report, published ahead of new unemployment figures this week, acknowledged there had been a jobs “enigma”, with increased employment despite stalled growth. One explanation is the number of employed people who are not in full-time, permanent jobs, said the CIPD.
The report predicted that the number of people employed on temporary contracts will continue to boost employment levels during the first quarter of the year.