Petraeus scandal deepens as top US general investigated General John Allen, commander of US forces in Afghanistan, has denied any wrongdoing and will keep his job while the matter is investigated. Photograph: Mohammad Ismail/Reuters The leading US commander in Afghanistan, General John Allen, is under investigation for alleged inappropriate communications with a woman at the centre of the scandal involving former CIA director David Petraeus, a senior US defence official said on Tuesday. The revelation threatens to fell another of the US military's biggest names and suggests that the scandal involving Petraeus - a former four-star general who had Allen's job in Afghanistan before moving to the CIA last year - could widen further than previously imagined. The American official said the FBI uncovered between 20,000 and 30,000 pages of communications - mostly emails spanning from 2010 to 2012 - between Allen and Jill Kelley, who has been identified as a long-time friend of the Petraeus family and volunteer social liaison in Tampa, Florida, with military families at MacDill air force base. It was Kelley's complaints about harassing emails from the woman with whom Petraeus had had an affair, Paula Broadwell, that prompted an FBI investigation, ultimately alerting authorities to Petraeus's involvement with Broadwell. Petraeus resigned as CIA director on Friday. Asked whether there was concern about the disclosure of classified information, the 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. The US defence secretary, Leon Panetta, said in a statement given to reporters flying with him to Australia that he had asked that Allen's nomination to be commander of US European command and supreme allied commander Europe be delayed "and the president has agreed." Allen, who is in Washington, was due to face a Senate confirmation hearing on Thursday, as was his likely successor in Afghanistan, General Joseph Dunford. The FBI referred the case to the Pentagon on Sunday. The US defence official said Allen denied any wrongdoing and that Panetta had decided to keep him in his job while the matter was under review. "While the matter is under investigation and before the facts are determined, General Allen will remain commander of Isaf [International Security Assistance Force)," Panetta said. Only hours earlier, Panetta had said he was reviewing Allen's recommendations on the future US presence in Afghanistan after most troops withdraw by the end of 2014. Commending Allen's leadership in Afghanistan, Panetta said in his statement: "He is entitled to due process in this matter." He also noted that he wanted the Senate to act "promptly" on Dunford's nomination. Evidence that the case involving Petraeus was not fully closed came late on Monday when FBI agents searched Broadwell's house in Charlotte, North Carolina. Agents entered the house carrying boxes and about four hours later took away what appeared to be two computers and about 10 boxes. During the search, agents inside could be seen moving through rooms, gathering materials and taking photos. They did not comment to reporters gathered outside the house. Broadwell's family was not at home at the time of the raid. The FBI and a justice department official would not comment on the reason for the raid. US officials had said in recent days their investigation was largely complete and that prosecutors had determined it was unlikely they would bring charges in that case, which started when Kelley contacted an FBI agent in Tampa about receiving harassing emails from an anonymous source. That FBI agent, who has not been identified, has also come under scrutiny after it was discovered he had sent shirtless photographs of himself to Kelley, but "long before" this investigation, a law enforcement official told Reuters. The photographs were first reported by the Wall Street Journal. The agent had never been on the Broadwell case, but had taken the information about the emails to the FBI cyber squad in Tampa, the law enforcement official said. The FBI agent who works in the Tampa office apparently became frustrated at the pace of the investigation and complained to a member of Congress, the official said. The FBI investigation of the emails received by Kelley traced them to Broadwell and subsequently uncovered emails that revealed an affair between Broadwell and Petraeus. The emails between the two women were of a "childish," jealous nature and showed some oneupmanship of trying to come across as being more important to Petraeus, the official said. When Petraeus resigned as CIA director on Friday he publicly admitted to having engaged in an extramarital affair. Lawmakers and others have questioned whether Broadwell, who co-wrote a biography of the decorated former general, obtained classified information from him or another source. Panetta had earlier said Petraeus did the right thing by stepping down, given potential security concerns, even as he said he was saddened by the end of the retired general's distinguished career.