U.S. Customs and Border Protection officials said Thursday that they are investigating a document that instructs federal border agents in Washington state to profile people of Iranian, Palestinian and Lebanese backgrounds.

The Northern Light, a weekly community newspaper in Blaine, Wash., published the unauthenticated document Wednesday, characterizing it as “a bulletin issued by the tactical analytical unit (TAU) in U.S. Customs and Border Protection’s Seattle Field Office,” which the newspaper said it obtained from an anonymous source via an immigration attorney.

CBP officials in Blaine detained dozens of Americans and green-card holders of Iranian heritage this month as they tried to return to the United States from Canada over the course of two days. Some said they were detained for up to 12 hours and reported being questioned about their contacts in Iran and whether they had served in the Iranian Revolutionary Guard Corps, even though they had immigrated to the United States decades ago, before the Revolutionary Guard existed.

CBP at the time denied that travelers were held up at the border on the basis of national origin and denied that there was a directive to do so. The Northern Light article suggests that CBP issued the purported directive the day before the mass detentions occurred.

Jason Givens, a CBP spokesman, declined Thursday to confirm or deny the authenticity of the document and said that “CBP does not comment on leaked documents.”

Dan Tanciar, acting director of CBP’s Office of Field Operations, which oversees the country’s ports of entry and airport arrival areas, told reporters Thursday that the alleged profiling incidents were “under investigation” but declined to provide more details.

U.S. officials warned this month that Iran could retaliate for the U.S. military’s killing of one of Iran’s most prominent military commanders, Maj. Gen. Qasem Soleimani, who led the Iranian Revolutionary Guard Corps’ elite Quds Force.

The Department of Homeland Security, which oversees U.S. border and immigration authorities, updated its security advisory on Iran just after Soleimani’s on Jan. 3 killing, warning that Iran and its partners had “demonstrated the intent and capability to conduct operations in the United States” and that such attacks could “come with little or no warning.”

The document published by the Northern Light is headlined “UPDATED PROCEDURES,” in reference to Soleimani’s death, and declares “Threat Alert High.”

The tactical analytical unit of the Seattle field office and the tactical terrorism response teams will be working with “frontline” officers to vet all people ages 19 to 59 who have any “link” — which the document defines as place of birth, travel or citizenship — with Iranians, Palestinians or Lebanese, it says.

The document text is grammatically incorrect and confusing, drawing a vague link between the Shiite sect of Islam — Iran’s official and majority religion — and membership in its special forces.

“Even if they are not of SHIA faith, anyone can state they are Baha’i, please question further to determine this is the case,” the document states. “What NTC [CBP’s the National Targeting Center] is looking for is membership in a specialized unit — QUDS forces; however, this group is so elite and well trained to evade. Anyone can state they are from a different faith to mask their intentions. TAU recommends scrutiny on military questions. We have not yet had anyone admit being in IRGC or Quds forces yet.”

CBP’s Tanciar told reporters Thursday that “there is no policy …. there is no rule that would permit us to target or stop individuals based on their nationality alone.”

“We have lots of facts that we have to cover. But that specific incident you raised is under investigation,” he added.

Reports about the document sparked outrage among Democrats and civil rights activists.

Rep. Pramila Jayapal (D-Wash.) said she requested “an immediate meeting with the CBP Seattle Field Office director” and that her office was working to verify the document.

“It is becoming increasingly clear from multiple conversations with travelers and CBP staff that there was, indeed, a directive from the Seattle Field Office to target Iranian Americans for secondary screening based on their country of origin and despite the fact that they were largely American citizens, legal permanent residents and legal visa holders,” she said in a statement.

Hugh Handeyside, the senior staff attorney with the American Civil Liberties Union’s National Security Project, said the document, if authentic, indicates that “the agency did, in fact, wrongly direct officers to target and detain travelers based on national origin, and interrogate them about their religion and beliefs.”

“If this report is true, CBP has been caught in a lie,” Handeyside said in a statement.

The ACLU is suing CBP for more information on the tactical terrorism response reams referred to in the document.