The number of confirmed E. Coli food poisoning cases linked to Chipotle Mexican Grill Inc in Oregon and Washington state rose to 35 on Tuesday, as the company announced steps to improve food safety.

Chipotle, which is grappling with its third food safety incident this year, has closed all its 43 restaurants located in and around Seattle and Portland because of the E. coli O26 outbreak.

Eight Chipotle restaurants have been tied to the outbreak. The company on Tuesday said it is deep cleaning and fully sanitizing the temporarily shuttered restaurants and replacing all food in them.

Chipotle is also testing the food in its Washington and Oregon restaurants and distribution centers, and it has hired two food safety consulting firms to assess and improve its food safety standards.

A company spokesman declined to say whether news of the outbreak has hurt sales at the popular burrito chain.

A dozen of the 35 confirmed cases involving Chipotle were in Oregon and the remainder were in Washington state, state officials said.

Two additional confirmed E. coli cases in Washington came from people who said they had not eaten at Chipotle before falling ill, officials said.

The current outbreak has resulted in 12 hospitalizations so far but no deaths, the state officials said.

The number of cases is expected to rise as more diners learn of the outbreak.

As of Monday afternoon, Washington health officials were interviewing an additional 25 people who became ill, said Dr. Kathy Lofy, the state's top medical officer.