WASHINGTON, July 20 — After months of behind the scenes wrangling, the White House said Friday that it had given the Central Intelligence Agency approval to resume its use of some harsh interrogation methods in questioning terrorism suspects in secret prisons overseas.

With the new authorization, administration officials said the C.I.A. could now proceed with an interrogation program that has been in limbo since the Supreme Court ruled last year that all prisoners in American captivity be treated in accordance with Geneva Convention prohibitions against humiliating and degrading treatment of detainees.

An executive order signed by President Bush allows the C.I.A. to use some interrogation methods banned for military interrogators but that the Justice Department has determined do not violate the Geneva strictures.

In a message to agency employees on Friday, General Michael V. Hayden, the C.I.A. director, said the executive order allows agency employees to “focus on our vital work, confident that our mission and authorities are clearly defined.” General Hayden said that information obtained through the interrogation program had been “irreplaceable,” though he said extraordinary techniques had been used on fewer than half of about 100 prisoners who had spent time in C.I.A. custody.