Two major health insurers selling policies on the Covered California insurance exchange violated state law over the last year when they listed names of doctors in online directories who were not part of their networks.

Results of a five-month-long investigation into the practices of Blue Shield of California and Anthem Blue Cross of California by the Department of Managed Health Care released Tuesday revealed that:

Department spokesman Rodger Butler said the results have been referred to the department’s Office of Enforcement for corrective action and possible financial penalties. The department also plans to do a follow-up survey in six months to ensure that the companies are complying with the Knox Keene Act, which regulates health care plans in California.

Since January, when the new plans under the nation’s health care law took effect, widespread consumer outrage over the inaccurate lists led to dozens of Blue Cross and Blue Shield customers filing complaints with the state.

Anthony Wright, executive director of Health Access California, a consumer advocacy group, said in a statement: “The results of the investigation are deeply troubling. If significant numbers of doctors listed aren’t where the insurers say they are, that’s a big violation of trust to premium-paying patients.”

The report comes as 1.1 million Californians who enrolled in health plans since last fall under the Affordable Care Act, also known as Obamacare, have three months to re-enroll — either in the same plan or a different one.

Officials at Covered California are hoping another 500,000 additional people will sign up for a private insurance plan by the Feb. 15 enrollment deadline.

Spokesmen for both Anthem Blue Cross and Blue Shield on Tuesday released statements saying that their companies acknowledged there were problems with the directories. But both said that they have taken significant steps to improve their accuracy.

But according to the new report, both companies told department officials that the survey’s methodology was flawed.

Steven Weissberg, a 52-year-old self-employed technologist from Benicia, said he expects the insurers’ directories will continue to have problems.

He said the Anthem Blue Cross plan he signed up for through Covered California in August listed four of his doctors. But when he called their offices, he was told they would not accept his plan.

“It’s a poison pill — they are forcing you into out-of-network coverage,” said Weissberg, who is now considering joining a Kaiser Permanente HMO instead.

Contact Tracy Seipel at 408-920-5343. Follow her at Twitter.com/taseipel.