The federal government will ban the sale of ground beef tainted with six toxic strains of E. coli bacteria that are increasingly showing up as the cause of severe illness from food.

Officials have been under pressure from food-safety advocates and some elected officials to do more to keep the potentially deadly bacteria out of meat, but the beef industry said the move was not needed and could force the price of ground beef to rise.

The new rule, which officials said would be announced Tuesday, means that six relatively rare forms of E. coli will be treated the same as their notorious and more common cousin, a strain called E. coli O157:H7. That strain has caused deaths and illnesses and prompted the recall of millions of pounds of ground beef and other products. It was banned from ground beef in 1994 after an outbreak killed four children and sickened hundreds of people.

"We're doing this to prevent illness and to save lives," said Dr. Elisabeth Hagen, the head of food safety for the Agriculture Department (USDA), which regulates meat. "This is one of the biggest steps forward in the protection of the beef supply in some time."

It is not illegal to sell fresh meat or poultry containing most toxic bacteria, like salmonella; they are frequently found on meat sold in supermarkets, and thorough cooking typically kills the pathogens. But since the 1994 outbreak, which involved hamburgers served at Jack in the Box restaurants, regulators have treated E. coli in ground beef differently.

Many people eat rare or undercooked ground beef, and if it is tainted, resulting illnesses can be deadly. Toxic E. coli, in its most common O157 form, is so virulent that just a few organisms can make people violently sick. The toxic E. coli live in the digestive tracts of cows and can get on meat during slaughter. It can cause bloody diarrhea, stomach cramps and, in severe cases, kidney failure.

In recent years, scientists found that several other strains of E. coli in food were also making people sick, and they identified the six most potent, called the Big Six non-O57s. Beginning at least four years ago the USDA began considering extending its ban to those additional toxic strains.

But the American Meat Institute, an industry group, has argued that safety measures already in place are sufficient. On Monday, the group was critical of the extended ban.

While several outbreaks caused by the Big Six E. coli strains have been linked to produce, the group pointed to only one having been related to ground beef. In that outbreak, last year, three people fell ill.

The Centers for Disease Control and Prevention estimate that E. coli strains other than O157:H7 cause nearly 113,000 illnesses each year, one-third of which can be attributed to tainted meat, according to USDA officials. Until recently, few cases were reported, however, because most medical labs were not equipped to test for the less common forms of E. coli.

The USDA will begin enforcing the rule in March, to give the meat industry time to prepare. The rule will apply to hamburger meat and trim or beef scraps that go into it, as well as some other products, like steaks that have been tenderized with machines that use needles to poke minute holes in the surface.

Some meat processors have begun to test for the six strains in recent months in anticipation of federal action, and many others will most likely begin testing once the government begins its own testing.