A Northern Virginia man accused of overseeing a front group for the Pakistani intelligence services — and using political contributions to lobby Congress for two decades — pleaded guilty to conspiracy charges Wednesday.

Syed Ghulam Nabi Fai, 62, acknowledged receiving funding from the Pakistani government, as well as committing tax violations, according to court documents filed in U.S. District Court in Alexandria.

Since approximately 1990, Fai received at least $3.5 million from the government of Pakistan, including its Inter-Services Intelligence agency, but failed to report the origin of that funding as required by law, according to prosecutors.

“For the last 20 years, Mr. Fai secretly took millions of dollars from Pakistani intelligence and lied about it to the U.S. government,” U.S. Attorney Neil MacBride said in a statement. “As a paid operative of ISI, he did the bidding of his handlers in Pakistan while he met with U.S. elected officials, funded high-profile conferences, and promoted the Kashmiri cause to decision-makers in Washington.”

Fai, of Fairfax, was the the longtime executive director of the Kashmiri American Council, which described itself as a Washington-based nonprofit group whose activities focused on the disputed territory of Kashmir. Fai faces up to eight years in prison. A sentencing hearing is scheduled for March 9.

Prosecutors said that the KAC was a cover group for the Pakistani government and that Fai, during the course of a long-running FBI investigation, made a series of false statements about Islamabad’s role.

The Pakistani government denied having a relationship with him, and prosecutors dropped a charge that Fai had acted as the agent of a foreign government without registering with the Justice Department.

Nina Ginsberg, Fai’s lawyer, said her client acknowledged receiving funds from officials who were agents of the ISI, or at least purported to be, but that he maintains that that funding “never affected the work that he did or the message that he put out.”

In a statement, Fai said the he had “made personal mistakes that I deeply regret . . . but I have never compromised our goals of independence and self-determination for the Kashmiri people and our commitment to peaceful negotiations between India, Pakistan and the leadership of the Pakistani people.”

Investigators said the case should serve as a warning to others who might consider concealing foreign lobbying efforts.

“Mr. Fai purposefully hid financial transactions from the U.S. government with intentions that his scheme to fund lobbying efforts by a foreign government would go unnoticed,” said James McJunkin, assistant director in charge of the FBI’s Washington Field Office. “The FBI will detect and defeat those who attempt to surreptitiously exert foreign influence on our government by using agents who conceal their foreign affiliation.”

In July, prosecutors filed charges against a second suspect in the case, Zaheer Ahmad, who remained at large. This fall, Ahmad was reported to have died at a hospital in Islamabad, but the charges are still pending in District Court in Alexandria.