9 September 2011 Last updated at 11:32 ET

Libyan conflict: The final phase?

By Jonathan Marcus BBC diplomatic correspondent

Wishing to avoid a blood-bath, Libya's new government, drawn from the National Transitional Council, has set a deadline of Saturday, for pro-Gaddafi forces in key towns like Sirte and Bani Walid to surrender.

Efforts have been under way through tribal leaders and other intermediaries to secure their peaceful hand-over. So far the results do not look encouraging.

Pro-Gaddafi forces in these towns have nowhere to hide. Some members of Colonel Gaddafi's regime have made it over the border into Niger. But the troops besieged in the coastal town of Sirte and further west in Bani Walid, some 90 miles south-east of Tripoli, are trapped. A resumption of the anti-Gaddafi forces' offensive could herald the last stand of the Gaddafi regime.

Partial let-up

For all the talk of a pause by rebel commanders on the ground, the reality is that there has only been a partial let-up in the conflict. For one thing, anti-Gaddafi forces have been pushing ever-closer to Sirte and Nato air war has been continuing much as before. Indeed over the past 10 days pro-Gaddafi forces have suffered regular attrition, as Nato patrols have been able to focus their attention on relatively defined areas.

The nature and scope of the targets that Nato claims to have hit gives a good indication of the sorts of forces that remain in and around Sirte and Bani Walid. Britain's Royal Air Force has played a prominent part. Over the past week its daily operational updates have presented a geographical snap-shot of the locations of the bulk of the remaining forces loyal to Colonel Gaddafi.

In and around Bani Walid, buildings used as depots for military vehicles have been hit; a military command and control installation; and a large barracks.

In Sirte tanks, artillery and armoured personnel carriers have been destroyed, weapons and ammunition stores are claimed to have been destroyed; and a variety of other vehicles have been hit.

South-west of Waddan, some 280 kilometres south of Sirte, eight command and control centres have been attacked and tanks, multiple launch rocket systems and artillery support vehicles have been targeted.

And at Sabha - also well to the south - a surface-to-air missile depot near to the airfield, which intelligence suggested was still being used as an active military base, was hit.

More recently, according to Nato sources, ground-to-ground Scud rocket launchers have also come under attack.

In addition to those air operations where weapons were actually released, the Royal Navy has been engaged in psychological operations; firing star shells to illuminate pro-Gaddafi forces' positions in and around Sirte, in the words of a British military statement "to demonstrate to those forces which persist in prolonging the conflict that their positions are well known and capable of being targeted".

Civilian casualties

The slow-down in rebel military operations has privately been welcomed by Nato officials, giving an opportunity to try to bring about a negotiated end to the fighting while allowing Nato air power to maintain the pressure on the Gaddafi loyalists.

The problem of course is what happens if an all-out ground assault is indeed launched against the remaining pro-Gaddafi enclaves. Every Nato press statement listing the attacks of the past week has stressed that the targets remain pro-Gaddafi forces that are threatening the civilian population. This of course has been the Nato line all along.

Nobody knows how many civilians remain in places like Sirte and Bani Walid. One Nato source told me that they believed there had been no mass exodus, adding that it was not clear if this was because they feared leaving or had in fact been compelled to stay.

If the ground fighting extends into these towns there is a strong possibility of civilian casualties. Given that Nato's mandate is explicitly to protect civilians, a battle for Sirte and Bani Walid could raise some difficult questions at the alliance's headquarters in Brussels.

Porous borders

The scale of the fighting though may be limited. This is not akin to the German assault on Stalingrad. Nato sources believe that there may only be a few hundred pro-Gaddafi fighters in Bani Walid, though significantly more in Sirte. In the past defeated elements appear simply to have drifted away. Libya is a large country with porous borders.

The real fear may not be some kind of cataclysmic battle but that sufficient pro-Gaddafi forces may evade capture, perhaps fuelling a future insurgency against the new government in Tripoli. For now, this is only a potential threat but it could become a reality, especially if Colonel Gaddafi himself and his sons are not brought to justice.