Sen. Robert Menendez raised concerns with top federal health-care officials twice in recent years about their finding that a Florida eye doctor — a close friend and major campaign donor — had overbilled the government by $8.9 million for care at his clinic, Menendez aides said Wednesday.

Menendez (D-N.J.) initially contacted federal officials in 2009 about the government’s audit of Salomon Melgen, complaining to the director overseeing Medicare payments that it was unfair to penalize the doctor because the billing rules were ambiguous, the aides said.

Last year, in a meeting with the acting administrator of the agency in charge of Medicare and Medicaid, Menendez again questioned whether federal auditors had been fair in their assessment of Melgen’s billing for eye injections to treat macular degeneration, the senator’s aides said.

The agency had ordered Melgen to repay the $8.9 million, and at the time of both conversations, Melgen was disputing the agency’s conclusion. His appeal continues to this day.