The Department of Homeland Security's Office of Inspector General told members of the House on Tuesday that technological hurdles are preventing officials from tracking foreign nationals who overstay their visas.

DHS said Monday that more than 700,000 foreigners overstayed their visas in 2016, which a senior Trump administration admitted was a "problem" that needs to be addressed.

But in testimony to a House Homeland Security subcommittee, Inspector General John Roth said there are several reasons why tracking these overstays is difficult.

"Identifying and investigating potential visa overstays requires pulling data from dozens of systems and databases, some of which are not integrated and do not electronically share information," Roth said in his prepared statement about a recent audit of DHS.

"Access to real-time data is mired by system access restrictions, the need to retain up to 40 passwords, and systems that are not updated."

Roth added that officials at Immigration and Customs Enforcement aren't being trained to use the systems available to them to track overstays. And he said DHS is forced to rely on third-party departure data to see if people have left before their visa expires, which is "not always accurate."

Roth said these problems contribute to the more than 1.2 million visa overstay cases, wasted resources, and arrests of visa violators that only amount to 0.4 percent of those who overstay their visas.

The IG's office made a series of recommendations to improve the current IT system and ensure people are trained to spot visa overstays. DHS agreed with those recommendations.