WASHINGTON — In a blistering new attack, the health insurance industry said Sunday that health care legislation drafted by Senate Democrats would drive up premiums, rather than making coverage more affordable, as the White House contends.

A lobby for the industry, America’s Health Insurance Plans, focused its criticism on a bill likely to be approved Tuesday by the Senate Finance Committee.

“The overall impact will be to increase the cost of private insurance coverage for individuals, families and businesses above what these costs would be in the absence of reform,” said Karen M. Ignagni, president of the trade association.

Democratic aides on the Finance Committee disputed the conclusion. They said the bill would provide tax credits to millions of people to help them afford coverage. Moreover, they said, people could keep the coverage they now have if they wanted. In addition, they said, some provisions of the bill would reduce the administrative costs of insurance.

Ms. Ignagni cited a report done last week for her organization by PricewaterhouseCoopers, the accounting firm.

The report says that the cost of the average family coverage, now $12,300, will rise to $18,400 in 2016 under current law and to $21,300 if the Senate bill is adopted. Likewise, it said, the cost of individual coverage, now $4,600, will average $6,900 in 2016 under current law and $7,900 under the bill.

The study provides ammunition to Republicans attacking the legislation and might intensify the concerns of some Democrats who worry that the bill does not provide enough help to low- and middle-income people to enable them to buy insurance.

Scott Mulhauser, a spokesman for Democrats on the Finance Committee, said: “This report is untrue, disingenuous and bought and paid for by the same health insurance companies that have been gouging consumers for too long. Now that health care reform grows ever closer, these health insurers are breaking out the same tired playbook of deception. It’s a health insurance company hatchet job.”

Ms. Ignagni and PricewaterhouseCoopers said several provisions of the Senate bill would drive up insurance premiums.

First, they said, the bill would require insurance companies to sell coverage to all applicants and would prohibit them from considering health status in setting rates. But, they said, the penalties for going without coverage are modest, so the “individual mandate” is weak.

This creates “a powerful incentive for people to wait until they are sick to purchase coverage,” Ms. Ignagni said. Sick people with high medical expenses are likely to join the insurance pool, while healthier people may defer buying insurance, secure in the knowledge they can get it when they need it, the study says.

In addition, the study says, the bill would impose a new excise tax on high-cost insurance policies and new fees on insurance companies. The study, like the Congressional Budget Office, predicts that insurers will pass these costs on to their customers, in the form of higher premiums.

Finally, the study says, the bill would cut hundreds of billions of dollars from the projected growth of Medicare. To make up for these cutbacks, it says, hospitals and other health care providers are likely to increase charges to private insurers, which in turn would increase premiums charged to businesses, families and individuals.