An apparent U.S. Customs and Border Protection internal memo adds credence to the recent numerous complaints from Iranian-born Canadian and American citizens that they were questioned and held for hours at the Canada-U.S. border in Blaine, Wash.

Despite reports that up to 200 travellers of Iranian descent were detained at the Blaine Peace Arch crossing on Jan. 4-5, U.S. Customs Border Protection (CBP) has denied such allegations. It told CBC News that delays at that popular border crossing — between B.C. and Washington state — were due to staffing issues during a busy holiday weekend.

However, a memo obtained by CBC News instructs U.S. border officers in the Seattle Field Office to cast a wide net when interrogating travellers, following the U.S. assassination of Iran's top general, Qassem Soleimani on Jan. 3. The Seattle Field Office covers the Canada-U.S. border from Washington state to Minnesota.

According to the memo, the target list included people between the ages of 20 and 58 with various links to Iran and Lebanon, such as being born in one of the countries or having travelled there. Lebanon has close ties with Iran.

An excerpt from an apparent leaked U.S. Customs and Border Protection memo to border officers on who to stop for questioning after the U.S. assassinated a top Iranian general.

Blaine-based immigration lawyer Len Saunders provided CBC News with the memo. He said it arrived in a blank envelope at his office on Wednesday from an anonymous source.

Saunders believes he was sent the memo because he has been outspoken about the alleged treatment of Iranian-born travellers at the border, calling it unconstitutional.

"Somebody with an interest in what happened had enough courage to come to my office and drop off the smoking gun," he said.

A former CBP officer who worked in the Seattle Field Office viewed the memo and told CBC News it appears legitimate. CBP declined to comment on its validity, but never declared it a fake.

Blaine, Wash.-based Immigration lawyer Len Saunders alleges U.S. Customs and Border Protection's treatment of Iranian-born travellers was unconstitutional.

The memo, which is titled, "updated procedures," begins by telling officers to "conduct vetting" on anyone within the specified age group with ties to the countries listed below. It then lists "Iranian and Lebanese Nationals" and in a following line, specifies that they should be from the Middle East, Africa or Latin America or have ties to Afghanistan, Pakistan, Syria and Israel.

It also instructs border officers to vet "any other nationality that has travelled to Iran or Lebanon," which would include any Iranian-American or Canadian who has paid a return visit to their birth country.

Palestinians and Lebanese who may have travelled to and from Israel and Jordan must also be vetted, said the memo.

Security expert Phil Gurski has viewed the memo and said it's difficult to determine precisely whom U.S. border officers were directed to stop and question. And because the net appears to be cast so wide, border officers likely rounded up any traveller with ties to Iran, he said.

"You're going to err on the side of caution and you're going to basically stop as many people as you can that fit this very wide, poorly worded and wide-ranging set of criteria," said Gurski, a former analyst with the Canadian Security Intelligence Service (CSIS).

"Doesn't matter if you're a Canadian or American, you were born [in Iran], ergo you're an Iranian, ergo, you're a potential threat."

He said that there's nothing unusual about U.S. border officers being issued a new directive to vet certain travellers during a time of heightened tensions with another country. But Gurski said he objects to the way the directive is written.

"It targets a wide variety of people that is both inefficient and unnecessary."

CBP responds

CBC News sent the full memo to CBP for comment. Spokesperson Jason Givens responded by email that "CBP has understood Iran and its proxies to be a very capable adversary for some time," and that, as a result, some travellers may be referred for additional screening based on their activities, associations and travel patterns.

Givens also said that border officers "are trained to enforce U.S. laws uniformly and fairly and they do not discriminate based on religion, race, ethnicity or sexual orientation."

Givens also said that "nationalities are not ethnicities." When CBC News asked for clarification on this point, Givens declined to respond any further.

Social media posts that CBP is detaining Iranian-Americans and refusing their entry into the U.S. because of their country of origin are false. Reports that DHS/CBP has issued a related directive are also false. —@CBP

Last week, lawyer Saunders shared with CBC News an email written by a CBP officer which alleged that U.S. border officers were told to question and detain Iranian-born travellers.

The officer also said in his email that after the detainment of Iranian-born travellers made national news on Jan. 5, the new directive was suspended.

Saunders claims the leaked document is further proof that Iranian-born Canadians and Americans were unjustly detained at the border. He also said that all Canadians should care about what happened because, depending on world events, they could be on the next list.

"It's a slippery slope," he said. "The American government needs to be held accountable for these kinds of actions."

The U.S. Department of Homeland Security's Office for Civil Rights and Civil Liberties is investigating complaints of Iranian-American travellers being detained at the border.

CBP and Homeland Security declined to comment on the investigation.