The US-run ads in the Pakistani media asking for leads to Osama Bin Laden and other Al Qaeda operatives have yielded useful information, a US official said on Friday. The brief television spots flashed colour pictures of Bin Laden and his 13 most wanted henchmen while a voiceover in Urdu offered rewards of up to $25 million. "During the last couple of days, we got around 28 calls and a number of them gave useful information," US embassy spokesman Greggory Crouch said.