By David Lawder and Emily Stephenson

WASHINGTON (Reuters) - More than 100,000 veterans are experiencing waits of more than 90 days for appointments at medical centers run by the U.S. Department of Veterans Affairs, according to an internal audit released by the troubled agency on Monday.

The survey revealed that a scandal over cover-ups of long wait times at VA clinics, during which some veterans are said to have died, was broader and deeper than initially thought, prompting a new round of recriminations from lawmakers and veterans groups.

The agency said staff at 76 percent of facilities surveyed reported that they were instructed to misrepresent appointment data at least once.

The VA said it found that in mid-May, 57,436 veterans were waiting for appointments that could not be scheduled within 90 days, while about 43,000 had appointments more than 90 days in the future.

Over the past 10 years, 63,869 new enrollees in the VA healthcare system had requested appointments that were never scheduled, the VA said.

The agency said it was working to contact all of those people to try to expedite their care. With more than 1,700 clinics, hospitals and other facilities serving 8.9 million veterans, the VA operates the largest U.S. healthcare system.

Lawmakers from both parties expressed outrage at the findings, which deepen the political problems the controversy presents to President Barack Obama and fellow Democrats as they try to keep control of the U.S. Senate in November elections.

"The results of the VA’s report are appalling and disturbing," said Senator Kay Hagan, a Democrat who is in a tight re-election contest in North Carolina, a state that is home to many military retirees.

Republican House Speaker John Boehner called the findings "a national disgrace" and said the House of Representatives would pass a measure this week to let veterans seek private care at VA expense if they had to wait over 30 days for an appointment.

EMERGENCY MEASURES

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The VA's acting inspector general, Richard Griffin, said he was discussing evidence of possible criminal activity in the scandal with the Justice Department. "We have found some indications of some supervisors directing some of the methodologies to change the (appointment) times ... Whether or not, in the opinion of the Department of Justice, they rise to the level of criminal prosecution, is still to be determined in most instances," Griffin said.

He spoke during a Monday evening hearing held by the House of Representatives' Veterans Affairs Committee.

"I agree," Griffin said, in reply to a question by Representative Phil Roe if it was fraudulent for officials to claim bonuses by manipulating data."

Criminal investigators on his staff were probing 69 facilities in addition to Phoenix Arizona -- where the waiting times scandal emerged earlier this spring -- looking for who may have given orders to manipulate data, he added.

The VA said it was abandoning a two-week scheduling goal for appointments after finding it was "not attainable," and it suspended bonus awards for the 2014 fiscal year ending Sept. 30.

The agency also said it would take emergency steps to rush medical care to veterans, including hiring temporary staff, keeping clinics open later, sending more patients to private care providers and bringing in mobile medical units to some locations. It will freeze hiring at headquarters offices. Last week, VA acting Secretary Sloan Gibson said that at least 18 Arizona veterans had died while waiting for appointments.

An official with watchdog agency the Government Accountability Office, said on Monday a GAO review had identified one veteran who died this year before obtaining needed care.

(Reporting by David Lawder and Emily Stephenson; Additional reporting by Susan Cornwell; Editing by Doina Chiacu, Mohammad Zargham, Leslie Adler and Clarence Fernandez)