US Senator Robert Menendez of New Jersey, a Democrat and the powerful head of the Senate Foreign Relations Committee, has been indicted on corruption charges for a second time, the Justice Department announced on Friday.

The 69-year-old senator and his wife Nadine Menendez have been charged with "bribery offences in connection with their corrupt relationship with three New Jersey businessmen," the federal prosecutor in New York said.

The second corruption indictment of Menendez in a decade – the first ended in a mistrial – could pose a threat to the Democratic Party's slim hold on the Senate.

The indictment alleged that between 2018 and last year, Menendez took hundreds of thousands of dollars in bribes from three New Jersey businessmen in exchange for help in their businesses and legal cases.

Menendez's efforts included helping Egyptian-American businessman Wael Hana protect a business monopoly granted him by the Egyptian government, the indictment alleged.

"Among other actions, Menendez provided sensitive US Government information and took other steps that secretly aided the Government of Egypt," it said.

For the other two businessmen, Jose Uribe and Fred Daibes, Menendez was accused of promising to use his influence to intervene in separate Justice Department prosecutions of each.

It is the second major legal threat in a decade for Menendez, who has held his Senate seat since 2006. He previously stepped aside from his leadership position on the Senate Foreign Relations Committee when he was last indicted.

He was charged in 2015 with accepting bribes of private jet flights, luxury vacations and over US$750,000 in illegal campaign donations.

But the charges were dismissed three years later by the Justice Department after a deadlocked jury could not reach a verdict in the case. (AFP)