At least 23 people attempting to illegally cross the southern border in 2021 were on the terror watch list maintained by the FBI, according to a report.

Fox News on Monday revealed that U.S. Customs and Border Protection data shows that between Jan. 20 and Dec. 27, 2021, there were 23 border encounters with individuals whose names were on the FBI's Terrorist Screening Database.

Eleven encounters happened in Texas, four in Arizona, and eight in California, according to data Fox News reportedly obtained through a Freedom of Information Act request filed in December.

The terror watch list is maintained by the FBI's Terrorist Screening Center, which was established after the 9/11 attacks to consolidate several different terrorism watch lists. This watch list has information on people reasonably suspected to be involved in terrorism (or related activities)," according to the FBI.

In March, Fox News reported that House Republicans on the Oversight and Homeland Security committees had asked the Biden administration to make public the number of migrants encountered at the southern border who are on the terror watch list.

"Reporting indicates that multiple individuals with terrorist ties have been recently apprehended after illegally crossing the border, and that such encounters may be increasing," Reps. James Comer (R-Ky.) and John Katko (R-N.Y.) wrote in a letter to Department of Homeland Security Secretary Alejandro Mayorkas.

"The American people deserve to know whether President Biden’s weak border policies are allowing terrorists to enter our homeland," they said.

Republicans have argued for years that an unsecured southern border and rampant illegal immigration endanger national security by letting terrorists, drug cartels, human traffickers, and other criminal elements into the country. Former President Donald Trump, a Republican, won office in 2016 by bringing this issue to the forefront of his campaign, famously pledging to build a wall on the southern border and create other physical barriers to illegal immigrants.

Democrats say they also support border security, but have criticized hard-line Republican policies as unfair and exclusionary toward legitimate asylum-seekers. Democratic President Joe Biden, since assuming office in 2021, has worked to undo many of Trump's restrictive immigration policies and halted construction of the border wall.

Most recently, the Biden administration has announced it will end a Trump-era pandemic health order, called Title 42, which required migrants to wait outside the country for their asylum claims to be processed and gave expedited authority to border agents to deport those who entered the country illegally. The order will expire on May 23, but some administration officials have warned that illegal immigration will surge even higher once the policy is rolled back.

Officials estimate that as many as 18,000 additional migrants will be encountered at the border each day once Title 42 ends.

Illegal immigration has surged under Biden's watch as a result of perceptions that he is more lenient toward migrants than his predecessor. In March, border authorities arrested 210,000 migrants attempting to cross the U.S.-Mexico border, the highest number recorded since February 2000 and a 24% increase from the same month one year before, Reuters reported. About half of the migrants encountered in March were expelled under the Title 42 order, the report said.

Republicans and even some moderate Democrats have called on President Biden to delay rescinding Title 42 and have introduced legislation to that effect in the U.S. Senate.