BLAINE, Wash. — Iranian Americans returning to the U.S. claim they were detained at the Blaine border crossing over the weekend, a claim Customs and Border Protection denies.

The Seattle Times reports an advocacy group says some people returning from a Persian pop concert in Vancouver BC were held for as long as 11 hours Saturday night.

But Customs and Border Protection released a statement saying social media claims that the agency was refusing them entry because of their nation of origin are false.

An attorney for the Washington Chapter of the Council on American-Islamic Relations tells the Times he believes they were detained because of tensions caused by last week’s killing by the U.S. of a prominent Iranian general.

CBP says heavy post-holiday traffic and reducing holiday staffing led to some delays at the border.

Governor Jay Inslee tweeted that his office is “closely tracking reports” of possible detainments.