The Health Secretary has done "absolutely nothing" to respond to a report he asked for on cutting childhood obesity, a health committee has heard.
Professor Graham MacGregor, chairman of Action on Sugar and an expert in cardiovascular medicine, angrily told MPs that Jeremy Hunt would stand by his view that a "sugar tax" was a "regressive tax".
Mr Hunt is already embroiled in a row with the Commons health committee over suppressing evidence about the benefits of a "sugar tax".
Committee chairman and Tory MP Dr Sarah Wollaston has questioned whether political pressure has been exerted to prevent the release of a review on the issue by Public Health England (PHE).
At the start of the committee's hearing on childhood obesity on Tuesday, Dr Wollaston said: "The Committee is deeply disappointed that we have not seen publication of the detailed evidence review.
"We consider that that is obstructing this inquiry."
Prof MacGregor said a "sugar tax" will play a major role in reducing the incidence of obesity, including among children.
He said: "We were asked by Jeremy Hunt for a plan to prevent childhood obesity over a year and a half ago.
"We gave him a brief but very well-evidenced document with seven actions as to how he could prevent childhood obesity.
"Since then he has done absolutely nothing.
"In spite of going back to him 10 times, we're always fobbed off by Department of Health officials saying they are waiting for further information."
Prof MacGregor said there was evidence from Finland and Mexico that a sugar tax worked. There was also evidence that taxes on alcohol and cigarettes worked.
He told MPs: "I don't think we need any more evidence. We should put a sugar tax in straight away, particularly on soft drinks."
He said there was a need for "weapons" to make industry reformulate their drinks, adding: "We know that taxes work on alcohol and cigarette consumption, and they will work on sweetened soft drinks."
He said "we need a government who will do it" adding that the PHE report had been handled like some "incredible state secret".
He went on: "The regressive tax thing is just a desperate ploy by Jeremy Hunt to find something that says we should not do it."
The PHE review was originally expected to be published in July and Dr Wollaston wrote to Mr Hunt last month, asking him to reveal the findings ahead of a planned inquiry by the committee into childhood obesity.
But Mr Hunt argued that the review was "integral to ongoing policy development" and would be published later this year with a government strategy on childhood obesity.