Pakistani troops fighting the Taliban in South Waziristan have surrounded a key stronghold of Uzbek fighters, military officials say.

They say that the town of Kaniguram - one of the largest towns in the area - is also the "operational centre" of the Pakistani Taliban.

The army says its offensive against the militants is "making good progress".

But a US-based rights group warned of "catastrophe" if aid is not allowed in to help civilians trapped in the area.

In a statement released on Thursday Human Rights Watch said that Pakistani authorities should ensure that civilians who cannot escape the fighting should have sufficient access to basic necessities.

The group cites reports of people trying to escape the fighting before the onset of a harsh winter.

Tens of thousands of civilians have fled the conflict zone since hostilities broke out.

The army says that two medical camps have been set up for displaced families and existing basic health units are being upgraded.
The army has declared South Waziristan a closed military zone until the operation ends.

It also announced "substantial successes" on fronts in the Nawazkot and Razmak-Makeen areas, adding that 11 militants and one solider had been killed in the latest fighting. But analysts say that stiff resistance being put up by militants indicate that all is not going to plan for the army.

Journalists have been denied access to the area and so cannot verify army reports of fighting.