Electronic systems for tracking departures of immigrants and other foreigners from the United States could be installed at major US airports under a plan approved by a congressional panel this week.
The Senate Judiciary Committee voted 13 to 5 on Monday for an amendment to a wide-ranging immigration bill that would require the installation of devices to check immigrants' fingerprints at the 10 busiest US airports within two years of the legislation being enacted.
Checks are currently made on foreigners arriving and re-entering the US through airports, but not when they leave.
"It's just a matter of having records we can keep so we know where we're going," Republican Senator Orrin Hatch of Utah said of his successful amendment to the bill.
Advocates argued that the extra layer of screening would also help identify foreigners suspected of committing crimes or who are on terror watch lists.
But opponents expressed concerns it could lead to broader fingerprinting of travellers.
If such biometrics systems at major airports prove useful, they would begin at more airports across the US and eventually be used at land and sea ports as well, under the amendment.
During a session that extended into the night, the Judiciary Committee defeated several Republican attempts to narrow the bill, including efforts to limit some immigrants' access to federal programmes such as food aid and healthcare for the poor.
The panel added protections for young children of parents being deported from the US and approved additional screening for arrivals from countries or regions seen as a security threat.