WASHINGTON — The former chief security officer for the American Embassy in Libya on Wednesday told a House committee investigating the fatal attack last month on a diplomatic compound in Benghazi that his request to extend the deployment of an American military team was thwarted by the State Department’s Bureau of Diplomatic Security.

But a senior State Department official said after the hearing by the House Committee on Oversight and Government Reform that keeping the team would not have changed the bloody outcome in Benghazi because it was not based there but in Tripoli.

The clashing perspectives of witnesses was echoed in the partisan sparring of lawmakers, with Republicans accusing the State Department of shortchanging security at the compound and Democrats countering that the vast majority of security requests from there had been met.

The hearing never established what it might have taken to repel the Sept. 11 attack on the compound in Benghazi that killed Ambassador J. Christopher Stevens and three other Americans, or even if the American military team might have played a role in defending the compound if it had been in Libya.