The spokesman, who identified himself as Dr Asad, said that Khalid was being supported by the government.
The government, which was installed after winning elections on February 18, has encouraged peace talks involving Mehsud's Tehrik-e-Taliban Pakistan group and other armed groups in the northwest of Pakistan, but after a brief lull violence has again escalated in the region.
Earlier this week, Mehsud criticised the provincial government for recent military operations and threatened to attack it unless it quit by Tuesday.
The provincial government has rejected the demand, saying that it only called in troops after Mehsud's men killed 17 Pakistani soldiers near the town of Zargari.
Meanwhile, Pakistan's military said it had killed at least 10 fighters in fighting in the Hangu district around Zargari.
"Ten militants have been killed and five army troops injured since the launch of the operation," Major General Athar Abbas, spokesman for the military, told the AFP news agency.
Abbas said that the army had cleared Zargari and was now sweeping through surrounding areas, forcing manyfighters to flee to the adjoining tribal district of Orakzai, which borders Afghanistan.
The violence came as General David Petraeus, the senior US commander in Iraq, claimed that al-Qaeda may be diverting some of its fighters to the region from Iraq.
"There are unsubstantiated rumours and reflections that perhaps some foreign fighters originally intended for Iraq may have gone to the FATA,'' he said, referring to the Federally Administered Tribal Areas of Pakistan.
Pakistan recently said it was working to tackle al-Qaeda and the Taliban in the region bordering Afghanistan and would not allow foreign forces across its borders to carry out operations.