The official report into the causes of the horsemeat scandal has been shelved until at least the autumn, prompting criticism that the government is not doing enough on food safety.

The inquiry by Chris Elliott, professor of food safety at Queen's University Belfast, was announced by the Department for Environment, Food and Rural Affairs 16 months ago and was to have been completed by the spring. It is expected to highlight the impact of spending cuts on frontline enforcement and inspection in the food industry.

But sources have told the Guardian that its publication has been blocked amid government concerns that the public would be frightened by the idea that criminals were still able to interfere with their food.

Elliott said in December that the food sector had become a "soft touch" for criminals who knew there was little risk of detection or serious penalty and that the response of the Food Standards Agency (FSA) was insufficiently robust. He has also called for a new police force to combat food crime, saying the risks were so great that a dedicated unit staffed by senior police detectives was needed .

The horsemeat scandal was the largest food fraud of recent times. Millions of beef burgers, ready meals and packs of mince were withdrawn from supermarkets and fast food restaurants across the UK and Europe in 2013 when it was revealed that they had been adulterated on an industrial scale with undeclared horsemeat.

Elliott was asked to lead the UK inquiry, and is understood to have delivered his final conclusions to the government several weeks ago. Publication was scheduled for 22 July, sources say, but the new environment secretary, Liz Truss, blocked it after the cabinet reshuffle.

Tim Lang, professor of food policy at City University, London, said it was scandalous that the horsemeat report had not been published. "The government is nervous about it coming out because it reminds the European public of a disaster in our meat trade. It's also embarrassing for the Conservatives because Elliott wants to toughen up regulation, which is against the current tide," he said.

Taken together with the recent FSA board decision to keep the names of supermarkets and meat processors secret, "it marks a sad return to the old style of government that puts food industry ahead of protecting consumers," he added.

The shadow environment secretary, Maria Eagle, condemned the failure to publish the report. "The horsemeat scandal and the recent Guardian investigation into the poultry industry exposed clear failings in the food supply chain and a lack of consumer protection. That's why the government's continued delay in publishing the Elliott review is bad for consumers and bad for the industry."

"Consumers rightly deserve to know what they are eating, where it has been produced and that there is a robust response mechanism when serious incidents occur so that the regulator and the industry can deal with it effectively.

"The Government must show leadership to restore confidence in food industry and act on this review urgently before we face another food scandal," she said.

The report's findings are likely to embarrass ministers. The Guardian understands they are similar to conclusions in the interim report submitted last year highlighting the impact of deep spending cuts on frontline enforcement and inspection in the food industry. It said confusion reigned when the horsemeat scandal broke because the coalition had stripped the FSA of overall responsibility for the integrity of food.

The report concluded that the industry's own audits were inadequate to protect the public and that unless audits were unannounced, they were of little value. Elliott also told a conference of food experts in May he had been warned by a senior civil servant that his report into the horsemeat scandal was so hard-hitting the government might want to bury it. This week, he declined to comment other than to say he was still awaiting notification of the publication date.

Sources have said, however, that the No 10 communications team was concerned the public would be frightened by the idea that criminals were still able to interfere with their food. Fears of provoking "an Edwina Currie" moment – the then Tory minister created a scare about salmonella in eggs in 1988 – were raised over the FSA's recent proposal to name and shame supermarkets and chicken processors for their levels of contamination with another food poisoning bug, campylobacter. The agency climbed down from the proposal to name the firms after pressure from other government departments.

Concerns that the food safety report could be buried or delayed came as health officials said on Friday that an investigation had been launched into a national outbreak of salmonella enteritidis after cases affecting 156 people were being looked into in Hampshire, London, the West Midlands, Cheshire and Merseyside.

It is understood that eggs imported in liquid form from continental Europe are the focus of investigations as the suspected source of the outbreak. Genetic typing t ests have shown the UK outbreak involves a strain closely related to the salmonella that caused cases in Austria and France this year.

A spokesperson for Defra said the Elliott review would be published in due course, and explained the failure to publish it before the parliamentary recess: "The timing of the cabinet reshuffle meant that the new secretary needed time to consider the report properly before publication."

The spokesperson later added: "The Elliott review will be published shortly, when it can be put before parliament. There has never been any attempt to block it."

The confusion over different department's responsibilities when food scandals erupt was drawn into focus again by a Guardian investigation into alleged hygiene failings in the chicken industry last month. The health secretary, Jeremy Hunt, demanded the FSA inspect the abattoirs at the heart of our investigation just hours after the FSA said it was "content" that it had handled incidents correctly.

No 10 declined to comment on whether its press team had raised concerns about the impact of both the Elliott report and the FSA's survey naming and shaming stores and chicken processors, but a government spokesperson said: "We do not accept that the current division of responsibilities between Defra, the Department of Health and the Food Standards Agency undermines our ability to protect the public. It is normal for ministers to set policy and for others to enforce it – in this case the FSA."

Public Health England said there have been 55 cases of salmonella enteritidis in Hampshire, 25 in London, 33 in Cheshire and 43 in the West Midlands. In the case of Hampshire, 32 of the cases were linked to

The Real China restaurant in Eastleigh, which voluntarily closed last month. It has since reopened.

In Cheshire and Merseyside, 31 cases were connected with an outbreak at a Chinese takeaway. Of the 43 cases in the West Midlands, 34 were connected with the Birmingham Heartlands hospital outbreak, which led to the closure of eight wards.

The cases occurred as isolated clusters over several months and were dealt with locally. They are now being reassessed under a national investigation as being potentially linked, said PHE.

Additional reporting by Mark Tran