The FBI has arrested an agent of Pakistan’s spy agency ISI and his associate in Washington for impersonating as American officials over the last two years and ingratiating themselves with members of the US intelligence services.

Arian Taherzadeh, 40, and Haider Ali, 35, used their false and fraudulent affiliation with the Department of Homeland Security (DHS) to get close to members of federal law enforcement and the defence services. The duo who were arrested from a luxury apartment block were produced in court on Thursday.

Four members of the US Secret Service have been packed off on administrative leave in connection with the incident.

Taherzadeh also offered these individuals the use of what he represented to be "official government vehicles." In addition, he offered to purchase a USD 2,000 assault rifle for a United Secret Service Agent assigned to the First Lady's protective detail.

They offered access to a black GMC SUV, provided rent-free apartments, gave away iPhones, a drone, and other items as gifts in their two-year effort to get closer to federal law enforcement officials.

Haider Ali had told witnesses that he was affiliated with the Inter-Services Intelligence agency in Pakistan.

"We have not verified the accuracy of his claims but Ali made claims to witnesses that he had ties to ISI which is the Pakistani intelligence service," Assistant US Attorney Joshua Rothstein told the judge, according to a PTI report.

Ali once had a Pakistani visa and two Iranian visas, he suggested that an additional charge looms on the horizon, Rothstein said.

Ali had multiple visas from Pakistan and Iran, federal law enforcement officials said.

A report in the Washington Post said so far, the men are charged only with "false impersonation of a federal officer," though Mr Rothstein said on Thursday that the government would probably add a charge of "conspiracy."

Also read: Pak Supreme Court shows Imran Khan the door, opposition celebrates