(CNN) -- Three of the largest Sikh advocacy groups in the United States are opposing airport passenger screening measures they say require hand-searches of turbans, despite the use of electronic imaging technology.
The Sikh Coalition, United Sikhs and the Sikh American Legal Defense and Education Fund are lobbying members of Congress in an effort to pressure federal transportation authorities to re-examine a policy they say unfairly scrutinizes members of the Sikh community.
"Sikh Americans are already looked at differently in this country," said the Sikh Coalition's director of programs, Amardeep Singh. "Once you start pulling Sikhs aside for extra screening, it sends a message that the government is suspicious of them for the same reasons [other passengers] are suspicious of them."
The U.S. Transportation Security Administration adjusted security procedures in 2007 to include provisions for "bulky" clothing that includes headwear, according to an agency statement.
Removal of all headwear is recommended, it said, but the rules are meant to accommodate passengers who may not want to remove the items for religious, medical, or other reasons.
Transportation officials would not confirm whether "advanced imaging technology" can sufficiently see through turbans, citing security reasons.
Despite the advent of the advanced technology, transportation security officers are permitted to use "professional discretion" in determining if a particular item of clothing should be subject to further screening, according to the statement.
Authorities say the policy has remained unchanged since 2007, but Sikh advocacy groups argue that airport security procedures were recently ramped up to include extra screening for all turban-wearing passengers.
Singh said U.S. Sikh groups that had once observed "a patchwork of [airport security] policies" are now witnessing a process in which "all turbans are searched."
CNN was not able to independently verify that claim.