As many as 5 million UK workers may never retire, according to a survey by Barings Asset Management.
The firm's annual poll of more than 1,500 adults found that the number of people not planning to retire remained at a record high of 14%, the same proportion as last year and the highest figure since the survey started in 2008.
Uncertainty surrounding retirement planning also remains high with a third (34%) of non-retired people not knowing when they will retire - the equivalent of around 12 million people.
The findings revealed 'a bleak picture' for those aged over 65, Barings said, with around a third (30%) uncertain of when they will retire, compared to 18% last year.
Rod Aldridge, head of UK wholesale distribution at Barings, said it was apparent that retirement planning, especially among the over-65s, had become increasingly unpredictable over the last few years.
'In light of the recent changes to the pension system, the concern is that this age group may have to compensate for insufficient pension provision and financial planning,' he said.
'What's more, with the increasing longevity of the British population, such problems may become a growing trend.'
The research also revealed that a third (33%) of people - the equivalent of 12 million - have no pension at all.
Regionally, the North West had the highest proportion of people with no form of pension (41%), while London was found to have the highest proportion of people with a pension.
While the number of men with no pension has steadily declined, from 30% in 2008 to 25% in 2014, the number of women with no pensions has risen from 39% in 2013 to 41% this year. According to Barings, this illustrates a growing gender gap regarding pension provision.