The CIPD Labour Market Outlook: Spring 2014 also shows an increasing gulf between the sectors in attracting skilled workers. The survey of more than 1,000 CIPD members suggests public sector bodies are finding it harder to hire or replace skilled workers.
More than half (53%) of public sector employers report that a lack of applicants mean they struggle to fill high-skilled roles. This is compared to 37% in the private sector.
Tibbert, who is also president of the Public Services People Managers Association, told HR magazine the resurgence of hiring in the private sector is a threat to the public sector's retention.
"As the economy recovers, this is something that could get worse," she said. "We are still looking to make up huge sums of money in our budgets, so will be working with pay restraints for quite some time yet. How can we compete with large corporates' budgets? That's a question I don't have the answer to at the moment."
Tibbert did warn that comparisons between the sectors "are not always helpful", adding that the public sector is about more than just money.
"Treating people well, delivering services and making sure we re-skill people where possible is crucial," she said
CIPD chief economist Mark Beatson told HR magazine the drain of talent to the private sector will not be easy to stem.
"The pay freezes and restraints since 2010 have meant the public sector is lagging behind in terms of wages," he said. "The wider that gulf becomes, that harder it will be for public sector bosses to keep their top talent."