That has led some to push for broader inquiries under various authorities, possibly a select committee in Congress, a military court of inquiry, or a panel like the one created to investigate the Sept. 11, 2001, attacks.
Though he said he was speaking for himself, his views are understood to be shared by other senior members of the Liberal Democrats in government, who are also keen for some kind of broad inquiry into the subject.
Another Republican senator, Johnny Isakson, went further, expressing support for a broad inquiry into the whole issue.
A wide range of groups and individuals who were monitored by the undercover spies have been pressing for a broad inquiry.
The deputy prime minister said there was a stronger and stronger case for a broad inquiry with each passing day of revelations about the scale of mass surveillance by British and US security services.
Mr. Vershbow's remarks, the first muted criticism of the operation by an American official, came as grieving Russians buried the first of the gas victims, and as a handful of liberal Russian lawmakers called for a broad inquiry into the crisis.
The Italian government has launched its own investigation into VW's emissions testing regime, while the French carmakers association backed a call by the finance minister Michel Sapin for a broad inquiry into the industry, saying it would "confirm that French manufacturers respect all test proceedings existing in all the countries where they operate".
The Senate voted 90 to 8 last month for such a broad inquiry, a day after the administration reversed course and supported the idea.
We present a new conceptual framework for broad social inquiry that will promote deep stakeholder engagement.
Mr. Bush resists for now such a broad inquiry, which would be dangerous and unpredictable for the White House.
Only 31 Democrats voted for a Republican resolution to open a broad inquiry into Mr. Clinton.
