Federal prosecutors on Thursday filed a superseding indictment against the Democratic senator Bob Menendez, charging him with being an unregistered agent of the Egyptian government, a court filing showed. The New Jersey senator has thus far resisted calls for his resignation. His trial on corruption charges will begin next May. The superseding indictment, filed in Manhattan federal court, accuses Menendez of violating the Foreign Agents Registration Act, which requires people to register with the US government if they are acting as “an agent of a foreign principal”. As a member of Congress, Menendez was prohibited from being an agent of a foreign government, even if he did register as one. Messages left with Menendez’s Senate staff and attorney were not immediately answered. The indictment says the conspiracy occurred from January 2018 to June 2022. It alleges that in May 2019, Menendez, his wife and a business associate, Wael Hana, met an Egyptian intelligence official in Menendez’s Senate office in Washington. During the meeting, they allegedly discussed a US citizen who was seriously injured in a 2015 airstrike by the Egyptian military using a US-made Apache helicopter, the indictment says. Some members of Congress objected to awarding certain military aid to Egypt over that episode and the perception that the Egyptian government was not willing to fairly compensate the injured American, according to the indictment. Shortly after the meeting in Washington, the Egyptian official texted Hana that if Menendez helped resolve the matter, “he will sit very comfortably”. Hana, the indictment says, replied: “Orders, consider it done.” The new charge comes weeks after Menendez and his wife were accused of accepting bribes of cash, gold bars and a luxury car from three New Jersey businessmen who wanted the senator to help and influence over foreign affairs. The couple have pleaded not guilty. Hana, the business associate, pleaded not guilty last month to charges including conspiracy to commit bribery. The indictments said that while Menendez was chair of the Senate foreign relations committee, he took several steps to secretly aid Egyptian officials. They included ghostwriting a letter to fellow senators encouraging them to lift a hold on $300m in aid. He was also accused of passing along information about employees at the US embassy in Egypt and transmitting nonpublic information to Egyptian officials about military aid. Menendez, 69, has insisted that he did nothing unusual to assist Egypt and that prosecutors misunderstood the work of a senator involved in foreign affairs. Authorities who searched Menendez’s home last year said they found more than $100,000 worth of gold bars and over $480,000 in cash – much of it hidden in closets, clothing and a safe. More than 30 Senate Democrats – including his home state colleague, Cory Booker – have called on Menendez to resign. Menendez has remained defiant, telling his colleagues in a closed-door luncheon two weeks ago he will not leave the Senate. Menendez has not said if he will run for reelection next year. The congressman Andy Kim has jumped into the primary, and the head of Senate Democrats’ campaign arm, Gary Peters of Michigan, has called on Menendez to resign, signaling that he may not receive campaign assistance.