US military prosecutors have filed new charges against self-described 9/11 mastermind Khalid Sheikh Mohammed and four alleged co-conspirators held at Guantanamo Bay, reports say. The charges are expected to be formally unveiled later on Tuesday. All five defendants had previously been charged at Guantanamo over the attacks. But the charges were set aside as the Obama administration tried to move the trial into US civilian courts, a move which was reversed in April. Each of the five suspects will be handed at least eight charges, which include murder in violation of the law of war, attacking civilians, hijacking aircraft and terrorism, according to a letter notifying families of 9/11 victims quoted by news agency AFP. "The conspiracy charge details 167 overt acts allegedly committed in furtherance of the 9/11 attacks," the letter said. The defendants will be arraigned within 30 days, after a judge has been assigned to the case and officers are selected to form the tribunal, AFP reported. In April, President Barack Obama abandoned efforts to have the five tried by federal courts on US soil, citing political opposition. The Pentagon has previously said Khalid Sheikh Mohammed admitted to being responsible "from A to Z" for the 2001 attacks in New York and Washington which claimed more than 3,000 lives. The other defendants facing new charges include Walid bin Attash, Ramzi Binalshibh, Ali Abdul Aziz Ali and Mustafa Ahmed al Hawsawi. Mohammed was captured in Pakistan in March 2003 and was sent to the US detention centre in Cuba in 2006. US prosecutors say he has confessed to involvement in a host of terrorist activities in addition to 9/11. These include the 2002 nightclub bombing in Bali, Indonesia, the 1993 World Trade Center bombing, the murder of American journalist Daniel Pearl and a failed 2001 attempt to blow up an airliner using a shoe bomb. In a 2007 hearing, Mr Mohammed alleged that he had been tortured at Guantanamo Bay. CIA documents confirmed that he had been subjected to waterboarding - simulated drowning - 183 times. Source: BBC