WASHINGTON (AP) — Three million Americans signed up for Medicaid under President Barack Obama's new health care law as of the end of February, the administration said Friday, offering its first full accounting of how much the safety-net health program has grown since implementation of the law.

Many were newly eligible because of the law's Medicaid expansion, while others already eligible but not yet enrolled came forward due to publicity around the law and its requirement for individuals to carry insurance or risk paying a fine, analysts said. It brings to around 62 million the total number of people covered under Medicaid and the Children's Health Insurance Program.

The 3 million figure is incomplete because a handful of states didn't report their numbers, and it doesn't include sign-ups in March.

But together with the administration's announcement earlier this week that more than 7 million Americans had signed up for private insurance through the law's new online marketplaces, it allows administration officials to boast that the nation's new health care program has already covered 10 million uninsured Americans even in the face of unflagging Republican opposition.

"The increase in Medicaid enrollments across the country is encouraging, but more work is left to do to ensure that the millions of uninsured Americans eligible for these programs gain coverage," said Health and Human Services Secretary Kathleen Sebelius in a blog post.

About half the states have accepted a Medicaid expansion in the health law, and Sebelius said the administration would continue to work to get more states on board. And although open enrollment just ended for the private health plans offered through the health law's online exchanges, people can sign up for Medicaid anytime.

Three million is significantly lower than the number of people the administration previously said were "determined eligible" for Medicaid under the law. But the new number sifts out duplicate applications and renewals to arrive at a solid figure.

The Congressional Budget Office has estimated that 8 million Americans will sign up for Medicaid under the law by the end of this year, leaving the administration work to do to capture 5 million more people to reach that goal.

Data released Friday by the Centers for Medicare and Medicaid Services also shows wide variation from one state to another in how much enrollment has increased, even among states that accepted the Medicaid expansion. Overall, in states that adopted the expansion and where it was in effect in February, enrollment increased by 8.3 percent from October through February, while in states that didn't accept the expansion it increased 1.6 percent.