Pakistani security forces arrested 28 rebels and killed three civilians as troops backed by helicopter gunships continued a major operation against militants for a second day on Wednesday, a senior official said. Supplies to NATO and US forces in Afghanistan via the historic Khyber Pass remained suspended because of the operation, local administration chief Tariq Hayat told a news conference. The offensive in the lawless Khyber tribal region near the Afghan border was launched at dawn on Tuesday after a series of attacks by suspected Taliban militants on foreign military supply depots in northwest Pakistan. Hundreds of NATO and US-led coalition vehicles were destroyed in the militant raids in December. "The operation will continue until the militants are flushed out and the supply route is secured," Hayat said.