Business organizations yesterday denounced proposed federal rules designed to reduce repetitive strain and other "ergonomic" workplace injuries as "vague, scientifically unsound and a politically motivated end run around Congress."

If the Occupational Safety and Health Administration "continues down this route," said Randel Johnson of the U.S. Chamber of Commerce, "the business community is going to oppose them in court."

He also said business would seek assistance from Congress in blocking the rules.

The rules, announced by the Labor Department, would require any employer with a worker who reports an ergonomic injury to improve conditions in that part of the workplace--steps such as adjusting workstations or changing the height of equipment.

The rules also would require employers to restrict workloads of injured workers and give workers full pay and benefits while they are on light duty. Workers who are unable to work would receive 90 percent of pay and 100 percent of benefits. This protection would last up to six months.

The rules would also require all manufacturers and companies with workers who do manual lifting to have a program to identify ergonomic issues and teach employees what to watch for. This requirement would also cover any employer with a worker who has reported an ergonomic injury that qualified under the rule.

The rules, which OSHA said would affect 1.9 million workplaces and more than 27 million workers, have been the subject of a long-running battle between employers and the government.

Employers have argued that in many cases it is unclear what they can or should do to alleviate these types of injuries. They persuaded Congress to block earlier versions of the rules and to fund a study of the matter by the National Science Foundation, one of many that have been ordered. That study is in progress.

But officials of the Labor Department and the Occupational Safety and Health Administration said the matter had become too urgent for further delay.

"We are compelled to act. Employees are getting hurt. Workers are being sent home. People are suffering," said Charles N. Jeffress, assistant labor secretary for occupational safety and health.

OSHA estimates that the rule would prevent 300,000 musculoskeletal disorders annually. Each year about 1.8 million workers suffer injuries related to overexertion or repetitive motion, and 600,000 are injured badly enough to require taking time off from work, the agency said.

Business groups charged that the rules are so broad that they potentially cover virtually every workplace in the nation, and that they give employers little guidance as to what would constitute compliance.

"The standard is so badly written, so broadly written, that an employer is not going to know what to do," Johnson said.

In addition, compliance could be hugely expensive, business officials charged. While the Labor Department estimated the cost to industry at $4.2 billion a year, Food Distributors International, which represents food wholesalers and distributors, said the rules could cost its members alone up to $26 billion the first year and $6 billion annually after that.

These costs "would result in closed plants and warehouses and lost jobs, and . . . would be reflected in the cost of goods," said FDI Vice President Kevin Burke.

The proposed rules are scheduled to be published in the Federal Register this week and will be open for comment for 60 days. There will also be three public hearings. OSHA expects to issue a final rule next year.