WASHINGTON - Citing problems exposed by the Boston Marathon bombings, senators weighing amendments to a sweeping immigration bill agreed Tuesday to boost security provisions around student visas.

The Senate Judiciary Committee agreed by voice vote to an amendment by Republican Sen. Charles F. Grassley of Iowa meant to ensure that border patrol agents at U.S. ports of entry have access to information on the status of student visas.

The committee action follows recent revelations that a student from Kazakhstan accused of hiding evidence for one of the Boston bombing suspects was allowed to return to the United States in January without a valid student visa.

The student visa for Azamat Tazhayakov had been terminated when he arrived in New York on Jan. 20. But the border agent at the airport did not have access to the information in the Department of Homeland Security's Student and Exchange Visitor Information System, called SEVIS.

Grassley's amendment would require Homeland Security to certify that data from SEVIS is transferred into the databases used by Customs and Border Protection at U.S. ports of entry. If that is not done within 120 days of enactment, the issuing of student visas would be suspended.

"This will plug a loophole in terms of the tragic Boston Marathon bombing," said Sen. Charles E. Schumer (D., N.Y.), an author of the immigration bill. "It really strengthens the bill and shows that our bill . . . is going to make things better in terms of terrorism."

The committee also agreed to a second Grassley amendment aimed at cracking down on fraud in the student-visa program. Two of the Sept. 11 terrorists entered this country on student visas, and Grassley said that demonstrated problems with the program. His second amendment, also approved by voice vote, would tighten accreditation requirements for schools hosting foreign students and prohibit flight schools not certified by the Department of Homeland Security and the Federal Aviation Administration from offering student visas.

The action came as the Judiciary Committee met for a second day to plow through 300 amendments to a bipartisan immigration bill that would put the estimated 11 million immigrants living here illegally on a path to citizenship.