ISLAMABAD (AFP) - Pakistan has hailed progress in peace talks with the counry's main Taleban faction, but attacks claimed by mysterious splinter factions are threatening to undermine the process.

The Tehreek-e-Taleban Pakistan (TTP) declared a one-month ceasefire last weekend, but that was swiftly followed by a major attack in Islamabad and a bloody roadside bombing targeting security forces - both claimed by dissident groups.

Less than 48 hours after the TTP announced its ceasefire, a gun and suicide bomb assault on an Islamabad court complex on Monday left 12 dead, the first attack in the heavily guarded capital since 2011.

It was disowned by the TTP central command but claimed by a group calling itself Ahrar-ul-Hind, while Wednesday's roadside bombing in the northwest that killed six paramilitary troops was claimed by another renegade faction, Ansar-ul-Mujahideen.

Talks aimed at ending the TTP's seven-year insurgency resumed on Wednesday despite those blows, and on Thursday the government announced it was setting up a new committee to accelerate the process.

But the attacks have raised fears that the militant movement is splintering dangerously - though several analysts said they suspected the "new" factions were simply the TTP operating under another guise.