Democratic leaders of the House Energy and Commerce panel, citing new domestic spying claims, are urging careful examination of surveillance overhaul legislation that may delay progress on the measure.

Retroactive legal immunity to telecommunications companies being sued for helping with a government spying program is the major sticking point on legislation overhauling the Foreign Intelligence Surveillance Act currently in negotiations between the House and Senate.

In a letter to lawmakers Thursday, panel Chairman John D. Dingell of Michigan, and two subcommittee chairmen, Edward J. Markey of Massachusetts and Bart Stupak of Michigan, said claims by the chief of security at an unnamed wireless carrier that the company may have given a government entity access to all of its customers- communications, justified further delay in considering the legislation.

“Because legislators should not vote before they have sufficient facts, we continue to insist that all House members be given access to the necessary information, including the relevant documents underlying this matter, to make an informed decision on their vote,” the trio wrote.

Babak Pasdar, chief executive of a security firm who was hired to upgrade security at the unnamed telecommunications company, said he discovered a third-party security breach traced to a governmental office in Quantico, Va., home to a U.S Marine Corps base and the FBI Academy, the letter said.

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