Feb. 4 (Bloomberg) — Insurers participating in Obamacare may have to expand their plans to include more federally funded health clinics, safety-net hospitals and other medical providers used by low-income people, under a U.S. proposal.

Health plans offered through government-run insurance exchanges may be required to cover 30 percent of "essential community providers" in each county in 2015, an increase from 20 percent this year, according to a document obtained by Bloomberg News. The proposal will be outlined today in a letter to insurers from the Health and Human Services Department.

As millions of Americans join health plans created through the 2010 Patient Protection and Affordable Care Act, consumers and regulators are paying greater attention to the breadth of available coverage. Insurers say smaller networks of hospitals and doctors help contain costs and improve care. Providers serving low-income people have complained that exchange plans won't allow them to join the networks, said Sara Rosenbaum, a professor of health policy at George Washington University.