General John Allen, commander of the North Atlantic Treaty Organization (NATO) forces in Afghanistan, is under investigation for alleged inappropriate communication with Jill Kelley, a woman at the center of the scandal involving former CIA director David Petraeus. — Reuters WASHINGTON – The probe into ex-CIA director David Petraeus's extramarital affair has snared the top US general in Afghanistan, officials said Tuesday, as the widening scandal rippled through Washington. US lawmakers, who were shocked by Petraeus's sudden resignation over the affair just three days after President Barack Obama's reelection, will launch their own investigation Tuesday amid a torrent of leaked accusations. In the latest in a cascade of revelations, a defense official said the FBI probe into the affair had uncovered 20,000 to 30,000 pages of correspondence – mainly emails – between General John Allen, the top US commander in Afghanistan, and the woman who led the FBI to Petraeus's former mistress. The official said the correspondence included “inappropriate” emails between Allen and Jill Kelley, 37, a Florida socialite who notified the FBI when she began receiving threatening emails from Petraeus biographer Paula Broadwell. President Barack Obama has delayed General John Allen's nomination as NATO's supreme commander pending a probe into his email correspondence with a woman at the center of a sex scandal, a White House spokesman said Tuesday. “At the request of the secretary of defense, the president has put on hold his nomination of General Allen as SACEUR pending the investigation of General Allen's conduct by the Department of Defense IG (inspector general),” National Security Council spokesman Tommy Vietor said. Defense Secretary Leon Panetta said in a written statement issued to reporters aboard his aircraft, en route from Honolulu to Perth, Australia, that the FBI referred the matter to the Pentagon Sunday. Panetta said that he ordered a Pentagon investigation of Allen Monday. The Allen investigation adds a new complication to an Afghan war effort that is at a particularly difficult juncture. Allen had just provided Panetta with options for how many US troops to keep in Afghanistan after the US-led coalition's combat mission ends in 2014. And he was due to give Panetta a recommendation soon on the pace of US troop withdrawals in 2013. Asked whether there was concern about the disclosure of classified information, an official, on condition of anonymity, said: “We are concerned about inappropriate communications. We are not going to speculate as to what is contained in these documents.” But even the sheer volume of communication alone could raise questions. Allen and Kelley were exchanging around 30 pages of communication per day, on average. – Agencies