U.S. border officials are using a questionnaire about religion to harass Muslim travelers, a Muslim advocacy group charges. The Immigration and Customs Enforcement questionnaire was released by the Department of Homeland Security in response to a lawsuit by the Council on American-Islamic Relations, the Intercept reports.

The questions that were revealed -- the document was heavily redacted -- include "Have you participated in any formal religious training or schooling?" "What house of worship do you attend?" and "Do you have any relatives or friends who have been martyred fighting in the defense of your beliefs?" Derek Benner, deputy executive associate director of homeland security investigations for ICE, said the document's purpose is "to provide guidance to special agents who are called upon to conduct a certain type of investigatory review of persons."

CAIR's lawsuit argues that customs and border officials have unconstitutionally engaged in religious profiling, and that the questions contribute to a larger harassment of Muslim travelers. The suit was filed in 2012 on behalf of four Americans who say they were detained for their religious beliefs while crossing the U.S.-Canada border.

"There is very obviously a concerted effort to question and intimidate Muslim-Americans based on their religious beliefs," Gadeir Abbas, one of the attorneys representing the plaintiffs, told the Intercept. "The types of questions specifically asked of Muslim travelers at borders across the country are far too consistent for there to not be some type of overarching framework and direction being used to target them."

The questionnaire was revealed during a legal battle between CAIR and ICE over the information's release. While CAIR says the documents surrounding the instructions given to border officials are critical to the case and evaluating institutional profiling, ICE asserts that the release constitutes a security risk.

"Asking Muslim-Americans questions about 'martyrs' in their family when they're crossing the border doesn't serve any constructive purpose, especially when there's not even a clear definition of what the word means," Dawud Walid of CAIR told the Intercept.