Figures from the new quarterly Community Life survey published last week by the Cabinet Office showed that the proportion of people in England volunteering at least once a year increased from 65 per cent to 71 per cent between 2011 and 2012.
Nick Hurd, the Minister for Civil Society, said this spike - the first since 2005 - was not just the effect of volunteering associated with the London Olympics; the activity recorded predated the Games and involved millions of people, he said.
Prime Minister David Cameron hailed the results as proof of the success of the big society agenda and government programmes such as the National Citizens Service.
But Rob Jackson, a volunteering consultant, points out that the 2005 peak in volunteering was during the Year of the Volunteer, when there was a campaign to encourage people to give time. He suggests the current rise could be a similar blip.
"I hope this is a sustainable increase, but it is too early to say," Jackson says. "The Olympics probably had an impact, lifting the value of volunteering and the fact it is fundamental to society. We don't tend to recognise that volunteers are so critical."
Jackson says the economic downturn has made people more aware of volunteering through initiatives such as food banks.
"There is so much cutting back of public services that people are stepping in because the vulnerable are not being looked after properly," he says. "It is a bit backhanded to say 'isn't it brilliant that we have all these volunteers?' when the poorest and most vulnerable are not being supported as they have been in the past.
"The government wants to say it has increased on their watch as a direct consequence of policy and therefore of the big society, which at best is a stretch and at worst is just a marketing ploy."
The survey is based on 2,262 face-to-face interviews carried out between August and October 2012. The sample size is smaller than that of the Citizenship Survey it replaces, which collected data from about 9,000 people over a year. Figures from the new survey will be published quarterly.
Joe Saxton, co-founder of research consultancy nfpSynergy, says he is waiting to see the next quarter's results, when the Olympic effect will have faded.
"If someone interviews you in the middle of the Olympics and Paralympics to ask if you are doing any volunteering - when the newspapers are full of how volunteers are wonderful - your tendency to want to say yes is going to increase," he says.
Saxton says the social desirability bias - the tendency of respondents to give answers that will be viewed favourably by others - would have been enormously strong at the time the survey was carried out.
Nick Ockenden, director of the Institute for Volunteering Research, which is now part of the National Council for Voluntary Organisations, points out that both the coalition and the previous government have been keen to promote volunteering.
"Anecdotally, a lot of volunteer centres are telling us that they've had more inquiries over the past year or so. But these figures relate to just one quarter and a degree of caution should be applied.
"They do show quite a big jump. I don't think we could say the Olympics alone is responsible beyond the fact that interest in volunteering is very high."
Although the latest figures reverse the decline in volunteering since 2005, Ockenden says the fall has never been large: "The figures from the past decade have shown a remarkable resilience. We saw a decline in the past couple of years, but it was relatively modest."