PESHAWAR (AFP) - Security forces Saturday warned residents of Charbagh to leave the area ahead of a possible attack on militants there, officials said. The warning was made in leaflets dropped by helicopters on Charbagh town, 20 kilometres north of Swat, the area where the Army launched a full-scale operation against militants on May 8. Residents were advised by the leaflets to evacuate the area, a senior military official told AFP on condition of anonymity. He said This has been done to avoid collateral damage ahead of a possible military operation in Charbagh town, a Taliban stronghold. Commandos this month attacked Peochar Valley, a stronghold of Maulana Fazlullah, who has led a Taliban uprising to enforce Sharia law in Swat, but it was not immediately clear how much of the area remained under militant control. Another security official confirmed that leaflets had been dropped in Charbagh ahead of a possible ground and air offensive. There are intelligence reports about the presence of a number of important Taliban commanders in the area, he said. However, he did not give further details, citing security concerns. The official said that residents had begun leaving Charbagh, which has population of 20,000-25,000. Some of the heaviest recent fighting seems to have taken place in Bahrain, in northern Swat Valley, where security forces said Thursday they had killed nine militants, in fighting that left two soldiers and two civilians wounded.