Kathleen Sebelius, secretary of Health and Human Services, issued the warning in a letter to Karen Ignagni, the insurance industry's top lobbyist.
Ms. Sebelius said some insurers were notifying enrollees that their insurance premiums will increase next year as a result of the law's new benefits.
The Wall Street Journal reported Wednesday that some carriers are asking for total premium hikes topping 20% starting this month, and the carriers are attributing one to nine percentage points of the increases to new benefit mandates in the law.
"There will be zero tolerance for this type of misinformation and unjustified rate increases," Ms. Sebelius wrote. "We will not stand idly by as insurers blame their premium hikes and increased profits on the requirement that they provide consumers with basic protections."