May 16 (Bloomberg) — UnitedHealth Group Inc., once leery of the Patient Protection and Affordable Care Act's new health insurance exchanges, is starting new plans in at least two states as competition grows stiffer in the government-run marketplaces.

In Washington state, four insurers plan to sell for the first time on the exchange next year, including UnitedHealth. In Virginia, a local health plan owned by a hospital and physicians in Lynchburg has proposed to join Aetna Inc., Kaiser Permanente and WellPoint Inc. in 2015. And in Indiana, the health exchange's offerings may double to eight companies.

While the three states offer the first glimpse of a movement by insurers to embrace the exchanges, the heightened competition may not be enjoyed everywhere. Exchanges in West Virginia, Alabama and Mississippi offer plans from only one or two companies this year, for example. About 8 million people signed up for private plans using the marketplaces created by the Patient Protection and Affordable Care Act in 2014, beating projections, and at least 13 million are expected next year.