Regular gamblers were more than six times more likely to bet online during the coronavirus pandemic compared to before the health crisis, according to Bristol researchers.
The study found frequent male gamblers in the UK were particularly prone to online gambling during lockdown, more so than their previously reported betting habits.
Overall results from the research at the University of Bristol revealed men and women gambled less during lockdown, partly due to betting shops being closed, but some forms of gambling increased.
Online usage, including poker, bingo and casino games, grew six-fold among regulars.
Respondents who gambled occasionally before the start of the pandemic were found to be more than twice as likely to bet online during lockdown.
Those who struggled financially before the crisis were also more likely to report gambling during lockdown, according to the experts.
"This study provides unique real-time insights into how people's attitudes and gambling behaviour changed during lockdown, when everyone was stuck inside and unable to participate in most social activities," said lead author Professor Alan Emond.
"The findings reveal that although many forms of gambling were restricted, a minority of regular gamblers significantly increased their gambling and betting online.
"As with so many repercussions of the pandemic, inequalities have been exacerbated and particularly vulnerable groups were worse affected."
The comparative research used two online questionnaires during the first lockdown in 2020, which surveyed the same group of adults, aged 28 on average, who had previously been asked similar questions about gambling before the pandemic as part of the Children of the 90s study.
More than 2,600 adults responded and results revealed that during a lockdown men were three times more likely than women to gamble more than once a week.
Professor Emond, a public health expert, added: "The strong link between binge drinking and regular gambling is of particular concern, as they are both addictive behaviours which can have serious health and social consequences.
"With the wider availability of gambling through different online channels, vulnerable groups could get caught in a destructive cycle.
"A public health approach is needed to minimise gambling harms."
The research builds on other evidence, including a YouGov study, which found regular gamblers turned to new online options during lockdown.