Washington(CNN) The Department of Homeland Security inspector general's office has launched an investigation into the "policies and practices" of Customs and Border Protection, the agency said Thursday in response to a report that the federal government tracked activists, journalists and others related to the migrant caravan that gathered in Tijuana late last year.
On Wednesday, San Diego's NBC 7 reported it had obtained documents showing that CBP officials in the San Diego region kept a list of people to pull aside for further screening when crossing the US-Mexico border.
CBP acknowledged on Thursday that it identified people who may have had information related to two separate border incidents in the region, but said that "efforts to gather this type of information are a standard law enforcement practice."
"CBP does not target journalists for inspection based on their occupation or their reporting. CBP has policies in place that prohibit discrimination against arriving travelers and has specific provisions regarding encounters with journalists," said agency spokesman Andrew Meehan.
Meehan said that the investigation by the inspector general, in conjunction with CBP's professional responsibility office, had been launched to "to ensure that all appropriate policies and practices were followed."
Immigrant advocacy groups and lawmakers have raised alarm about the report, calling on the administration to provide answers.
In a letter to CBP Commissioner Kevin McAleenan, House Homeland Security Committee Chairman Bennie Thompson and Rep. Kathleen Rice, chairwoman of the subcommittee on Border Security, Facilitation, and Operations, requested answers about the report.
"The appearance that CBP is targeting journalists, lawyers, and advocates, and particularly those who work on immigration matters or report on border and immigration issues, raises questions about possible misuse of CBP's border search authority and requires oversight to ensure the protection of Americans' legal and constitutional rights," they wrote.
The American Civil Liberties Union denounced the targeting of journalists, activists and lawyers.
"This is an outrageous violation of the First Amendment. The government cannot use the pretext of the border to target activists critical of its policies, lawyers providing legal representation, or journalists simply doing their jobs," said Esha Bhandari, staff attorney with the American Civil Liberties Union's Speech, Privacy, and Technology Project, in a statement. "We are exploring all options in response."