California health regulators have demanded that 13 direct-to-consumer genetic testing startups halt sales in the state until they prove they meet state standards. The state Department of Public Health sent the cease-and-desist letters last week following an investigation spurred by consumer complaints about the tests' accuracy and cost, a department spokeswoman said Monday. Two of the most visible companies to offer consumer genetic tests - Redwood Shores-based Navigenics Inc. and Mountain View-based 23andMe Inc. - confirmed receiving the letters.

Health officials would not identify the companies involved until confirming they had received the letters but said all the targeted companies advertise on the Internet.

All the companies have two weeks to demonstrate to regulators that their laboratories are certified by the state and federal governments, said department spokeswoman Lea Brooks. The startups also must show the tests they are selling California residents have been ordered by a doctor as required by state law.

"There's either concern they don't have a license, there isn't a physician's order, or both," Brooks said. "That's what's under investigation."

Companies face fines of up to $3,000 a day.

The New York State Department of Health issued similar notices to nearly two dozen testing companies in April.

The crackdowns follow the launch of a batch of new DNA analysis services spawned by recent genetic discoveries. The mostly Web-based services will scan customers' genes to spot potential health risks, from cancer to lower back pain.

State and federal public health officials have urged consumers to be skeptical, pointing out that related research is in its earliest stages and doctors have little training in interpreting the results.

The federal Food and Drug Administration does not evaluate the tests for accuracy, though a federal panel recently recommended stepped-up oversight to ensure their validity.

A spokeswoman for 23andMe, which has financial backing from Google Inc. and Genentech Inc. described the company as an "informational service."

"What we do is offer people information about their genetic makeup, including ancestry and applicable scientific research," spokeswoman Rachel Cohen said. The company scans customers' DNA for about $1,000. Cohen declined to say Monday whether 23andMe had halted sales in California.

Navigenics charges $2,500 to screen nearly 2 million genetic markers in a DNA sample - typically a swab of saliva - for potential health risks.

In a statement released Monday, Navigenics said it believed it was in full compliance with California law. The company said it would submit details to regulators showing its labs were certified and its tests are ordered and reviewed by California-licensed physicians.