The already delayed childhood obesity strategy will not be published until the summer, the government has said – and campaigners say it is unlikely to include a sugar tax.

“It is a very complex issue and there is a lot of work going on to get it right,” said a Department of Health spokesperson. “There are a lot of different issues that need considering and we want to make sure it is right when we put it out. David Cameron and Jeremy Hunt have said they want it to be a game-changing moment.”

The news from the ministry will anger health charities and campaigners, who say there is an urgent need for action on obesity, including introducing a tax on sugared foods. Cancer Research UK accused the government of failing children, saying that every day counted.

“David Cameron has called children’s obesity a crisis and yet the government has failed the next generation by stalling on one of its own health priorities,” said Alison Cox, the charity’s director of prevention. “While the government delays, more children will become obese.

“Our survey shows people want the government to act to fight children’s obesity – eight out of 10 think it’s a problem. To help prevent thousands of cancer cases we want a ban on junk food ads during family viewing times, a sugary drinks tax and more sugar taken out of food. The future health of our children depends on strong action right now.”

The childhood obesity strategy was expected in December, but delayed amid speculation that the campaign for a sugary drinks tax – supported by the restaurateur Jamie Oliver, medical charities and the House of Commons health select committee – had become embarrassingly popular for a government disinclined to interfere with the market by imposing new taxes.

The launch of the strategy was then said to have been scheduled for January, which slipped to February or even March. Now the department says publication will be in the summer.

Ben Reynolds, of the Children’s Food Campaign, which has been working with Jamie Oliver to press for a sugary drinks tax, said: “It would be disappointing if a sugary drinks tax is not included.”

He said they understood that the government might instead intend to put pressure on the food and drinks industry to act by cutting sugar and making products healthier, with the threat of fiscal action if they do not comply.

If so, said Reynolds, “we would like to see a timescale and some metrics on how they judge that industry has responded. A vague threat is nothing without that.”

It appears increasingly unlikely that the measures in the obesity strategy will include a sugar tax, although both David Cameron and Jeremy Hunt – in a recent interview with the Guardian – have said that is not off the table.

The prime minister was said earlier this month to have scrapped the idea in favour of the threat of a levy on drinks companies if they did not reduce the sugar content themselves. Sources within the Department of Health said they did not expect a sugar tax, although they insisted they did not know the content of the strategy, which has not yet been finalised.

The delay in the strategy will cause great concern among health campaigners. Shirley Cramer, chief executive of the Royal Society for Public Health, said: “Childhood obesity is a time bomb on which the clock is ticking, set to wreck the future health of our children and the sustainability of our NHS. There can be no excuse for delay or prevarication when we know – and the government knows – what must be done, especially if those delays are for political reasons.”

Jane Landon, deputy chief executive of the UK Health Forum, said: “The government has pledged its firm commitment to tackling child obesity, but we simply cannot afford a delay in taking action. As the clock ticks, the prevalence of obesity continues to rise, adding to already unsustainable demands on health and social care services.”

Prof John Wass, the Royal College of Physicians’ special adviser on obesity, said: “The delay in publishing the strategy is extremely disappointing, and a hugely missed opportunity to save lives, improve patient care and save NHS funds.”

Prof Russell Viner, of the Royal College of Paediatrics and Child Health, said: “With every day that passes, more children are at risk of developing serious conditions associated with obesity. These include type 2 diabetes, high blood pressure and asthma. So yet another delay in the publication of the government’s childhood obesity strategy gives great cause for concern.”

The dental health of children was also highlighted on Friday night by an analysis from the Press Association which showed that thousands of young children have had decayed teeth removed in England’s hospitals over the last four years.

Overall, there have been 128,558 episodes of care for children aged 10 and under needing one or more teeth out since 2011.

Andrew Gwynne, the shadow public health minister, said: “It’s utterly unacceptable that at a time when the country is facing an obesity epidemic David Cameron is kicking his obesity strategy into the long grass.

“Unfortunately, it appears ministers are far more interested in listening to big business than to the health experts. The government needs to urgently rethink this delay and publish its strategy as soon as possible. Ministers should stop putting their political interests over those of the nation’s health.”

A voluntary levy on sugary drinks in Jamie Oliver and Leon restaurants has raised £50,000 so far, which will be distributed to health and educational causes.

Tam Fry, of the Child Growth Foundation, said: “This constant delay in publishing the childhood obesity strategy is unforgivable and the statement that they ‘want to get it right’ is the most ridiculous and lame excuse.

“The Department of Health, and No 10 who is pulling its strings, have had literally months to get it right and it is a fair bet that its essential elements have been finalised for some time.

“In the words of the England’s chief medical officer, Dame Sally Davies, the current epidemic is a national emergency, which should be tackled by immediate action at Cobra level and not put off at the whim of any politician. Health secretary Jeremy Hunt regards childhood obesity as a great scandal and has promised draconian and robust action to address it. But what have we got? Total inaction.”

Childhood obesity is of increasing concern to health experts. In 2013, 29% of children aged two to 15 in England and Scotland and 34% in Wales were either overweight or obese. In year six, just before children leave primary school, 20% of boys and 17% of girls were obese, according to figures collected by the child measurement programme.

Obesity is a risk factor for long-term health problems that are becoming an increasing burden on the NHS, such as type 2 diabetes, which now accounts for nearly 10% of the entire NHS budget.

• This article was amended on 26 February 2016. It originally quoted a Department of Health spokesperson as saying a sugar tax was unlikely. The department has subsequently said this was not the case.