The White House and the health insurance industry yesterday descended into open conflict on the eve of a critical Senate vote that could determine President Barack Obama's healthcare reform plans.

Supporters of Mr Obama accused the healthcare insurance industry of “sabotage” after it issued a PwC study arguing that premiums would rise much faster under proposed reforms than they would otherwise have. The 26-page report marked an abrupt end to the unlikely alliance between Mr Obama and America's Health Insurance Plans – the main industry lobby group, which has spent about $100m in advertising in favour of the reforms.

The report estimates that premiums for the average household would rise to $17,200 (€11,633) a year by 2013 under the proposed reforms as against $15,500 without the reforms. Today's average annual premium is $12,300.

“This is a transparent attempt by the health insurance industry to sabotage reform,” said Richard Kirsch, head of Health Care for America Now, the largest group advocating reform.

“Of course they're coming out with guns blazing at the 11th hour. They're out to protect their money and their power, and they'll go to any lengths – including circulating fake information – to stop real change.”

A spokesman for Max Baucus, chairman of the Senate finance committee, which is to vote today on its $829bn 10-year healthcare reform plan, described the report as a “hatchet job, pure and simple”.

The report identifies elements of the “Baucus plan” that would raise costs for average policyholders. These include steps reducing the number of Americans forced to take up health insurance by lowering the fine levied on individuals who declined to take out a policy.