WASHINGTON — The volume of emails uncovered between a top US general and the woman who triggered a probe that ended the career of CIA director David Petraeus is "astounding," a top senator said Tuesday.

"The number of emails between the two was sort of an astounding number of emails, but if you can get over that number, then the question is, 'hey, let the IG (inspector general) do the appropriate investigation," said Senate Armed Services Committee chairman Carl Levin, a Democrat.

"I'm not going to jump to conclusions about him."

But he said General John Allen, commander of US forces in Afghanistan, should not automatically resign because he was put under investigation over his correspondence with Tampa socialite and volunteer military liaison Jill Kelley.

"I think he ought to stay on unless there is some reason that's put forward that he's done something wrong," Levin said.

According to a senior Pentagon official, Allen denies any sexual liaison with Kelley, but the "sheer volume" of correspondence could be found to amount to "conduct unbecoming an officer."

In all, the Federal Bureau of Investigation is investigating 20,000 to 30,000 pages of Allen documents, a Pentagon official said.

The Washington Post said this represented between 200 and 300 emails between Kelley and the general.

Allen was placed under investigation after FBI agents probing threatening emails sent to Kelley by Petraeus's mistress, his biographer Paula Broadwell, stumbled upon a vast trove of "flirtatious" messages Allen had sent to Kelley.

Petraeus resigned last week after his affair came to light. The Broadwell emails to Kelley are suspected to have been attempts to ward off a supposed romantic rival.

Levin said he had "a long conversation" Sunday night with Defense Secretary Leon Panetta about the explosive scandals involving Petraeus and Allen.

Asked whether Panetta, who has expressed a desire to retire next year, should stay on longer due to the current state of flux of the national security team, Levin was noncommittal.

"If it's resolved fairly quickly (with Allen), then I don't know that that would change his timetable," he said of Panetta. "If it drags on for some length of time, then it might."

Dianne Feinstein, who heads the Senate Select Committee on Intelligence, said she knew little about the Allen probe or whether he might have revealed classified information to Kelley.

"I would be very shocked and surprised if that were the case," she said.

John Ullyot, a former spokesman of the Senate Armed Services Committee who is now a crisis management expert for public relations firm Hill & Knowlton, said he served with Allen in the US Marines in the 1990s.

"Everybody who knew him or served underneath him cannot believe this whatsoever. It's an absolute shock," he said of the Allen probe.

"He was known as kind of a warrior monk," he added. "With the possible exception of General Jim Jones, he had probably the most storied, modern-day Marine Corps career post-World War II."