Pakistan's Taliban movement, a major security threat to the country, is holding exploratory peace talks with the U.S.-backed government, a senior Taliban commander and tribal mediators told Reuters on Monday.

The talks are focussed on the South Waziristan region and could be expanded to try to reach a comprehensive deal.

The Taliban, which is close to al Qaeda, is making several demands, including the release of prisoners, said the commander. A tribal mediator described the talks as very difficult.

The United States, the source of billions of dollars of aid vital for Pakistan's military and feeble economy, may not look kindly on peace talks with the Tehrik-e-Taliban Pakistan (TTP), which it has labelled a terrorist group.

Past peace pacts with the TTP have backfired and merely gave the umbrella group time and space to consolidate, launch fresh attacks and impose their austere version of Islam on segments of the population.

Yes, we have been holding talks but this is just an initial phase. We will see if there is a breakthrough, said the senior Taliban commander, who asked not to be identified.

Right now, this is at the South Waziristan level. If successful, we can talk about a deal for all the tribal areas.

The TTP, which is allied with the Afghan Taliban movement fighting U.S.-led NATO forces in Afghanistan, is entrenched in the unruly tribal areas along the porous border.

Pakistan has come under pressure to eradicate militancy since U.S. special forces in May found and killed Osama bin Laden in a Pakistani town, where he had apparently been living for years.

(Writing by Michael Georgy; Editing by Ron Popeski)