HELENA, Mont. -

Insurance Commissioner Monica Lindeen has approved an Illinois company's plans to buy Blue Cross and Blue Shield of Montana.

Blue Cross is Montana's largest private health insurer with about 250,000 customers. Health Care Service Corp., a much larger company operating in four states, has offered $40 million for the nonprofit company.

Lindeen says her approval requires the company to keep all 450 jobs in Montana and to later add another 100. She said the company's expect to complete the acquisition quickly, which it says is needed to compete in a changing insurance marketplace.

Earlier in the week Attorney General Tim Fox gave his approval to the financial aspects of the deal, including that the proceeds of the transaction be paid to a new health care foundation that benefits the public interest.