Sen. Bob Menendez, D-N.J., was "severely admonished" by the Senate Ethics Committee on Thursday over gifts he received from Dr. Salomon Melgen and preferential treatment the lawmaker gave him and his business interests.

In a letter from the committee to Menendez, he is ordered to repay "fair market value" for the gifts Menendez received from the doctor, who was sentenced to 17 years in prison for Medicare fraud.

"The Committee has found that over a six-year period you knowingly and repeatedly accepted gifts of significant value from Dr. Melgen without obtaining required Committee approval, and that you failed to publicly disclose certain gifts as required by Senate Rule and federal law," the letter reads.

"Additionally, while accepting these gifts, you used your position as a Member of the Senate to advance Dr. Melgen's personal and business interests," the letter continues. "The Committee has determined that this conduct violated Senate Rules, federal law, and applicable standards of conduct. Accordingly, the Committee issues you this Public Letter of Admonition, and also directs you to repay the fair market value of all impermissible gifts not already repaid."

The letter is signed by Sen. Johnny Isakson, R-Ga., chairman of the committee, Sen. Chris Coons, D-Del., the ranking member, and four other members on the committee.

The ethics committee began its investigation into Menendez in November when the judge in his corruption trial declared a mistrial. The Justice Department dropped all charges against the New Jersey Democrat in late January.

Outside of the repayment of gifts, the letter does not affect Menendez's standing in the Senate. In February, Menendez regained his spot as ranking member of the Senate Foreign Relations Committee.