The battlefields of Kandahar and the conference rooms of Bonn were inextricably linked on Monday as Afghan leaders arrived in Germany to discuss a future government for Kabul.

The bloodier the battle over Kandahar, the last critical stronghold of the Taliban, the more slippery the diplomatic terrain in Bonn becomes, analysts say.

The United Nations has brought four Afghan groups together in Bonn with the aim of securing their agreement on a broad-based transitional government to take over Kabul from the Northern Alliance.

But finding agreement among the ethnically disparate factions that have been fighting each other for more than 20 years will be extremely difficult.

The Northern Alliance, the player with the biggest number of aces to lay on the table at the talks, is itself a deeply divided coalition of Uzbeks and Tajiks, whose only common interest has been the defeat of the Taliban.

The three other groups are: the so-called Rome group led by Mohammad Zahir Shah, the former Afghan king, who was deposed in 1973, and is expected to play a largely symbolic unifying role; the Peshawar group led by Pir Syed Gillani, the Pashtun leader backed by Pakistan; and the Cyprus group bringing together Afghan refugees and exiles backed by Iran.

Lakhdar Brahimi, the UN secretary general's special envoy for Afghanistan, envisages a transitional government to rule the country with the support and guidance of the UN for two years.

Diplomats say the Bonn meeting could result in the establishment of an interim transitional government that would last for only a few months. This would buy time for the creation of a more representative transitional authority and broad council, approved by a Loya Jirga (grand council of tribal leaders).

Taliban leaders excluded from the Bonn meeting, because of resistance from the Northern Alliance, could be included in later discussions expected to take place in Kabul, UN officials say.

Despite the change in the stance of Burhanuddin Rabbani, one of the alliances' top leaders, who now says he would accept Taliban representation in a future government, persuading the rivals to agree who will ultimately lead Afghanistan will be difficult.

Relations between the majority Pashtun tribes, which represent about 40 per cent of Afghanistan's 24m people, and minorities such as the Tajiks and the Uzbeks have become bitterly polarised over the past two decades.

The Pashtun, who have ruled Afghanistan since the 18th century, are now having to face up to the reality of being forced to share power with these groups in the form of the Northern Alliance.

The success of the Bonn conference to a large degree depends on the willingness of the alliance to compromise, diplomats and analysts said.

"Afghanistan's problem is that its minorities have become emboldened because they have tasted power through their participation in the anti-Soviet resistance, said Hasan Askari Rizvi, a leading Pakistani commentator on regional security.

"Balancing political power to satisfy all the major parties has become a difficult challenge."

Others warn that the disparate groups that opposed the Taliban - still holding together in the drive for military spoils and under pressure from Washington - may begin pulling in opposite directions once US troops leave Afghanistan. Many fear a civil war might break out if its leaders fail to settle on a peace formula.

"Afghans are armed to their teeth, they will resist and fight unless there's a power-sharing formula acceptable to all concerned," Marika Vicziany, Director of the Asia Institute at Australia's Monash University warns.

The main carrot the UN has to dangle in front of the groups in Bonn, is the promise of reconstruction aid which diplomats estimate could be as much as $12bn.

Securing those sums will be the subject of a meeting sponsored jointly by the World Bank, the Asian Development Bank and the UN's Development Programme, to begin on Tuesday in Islamabad, Pakistan's capital.

The civil war sparked after the 1989 retreat by the former Soviet Union, following a decade-long occupation, was partly the result of a failure to pay for the reconstruction of a country whose war was financed by the western world, diplomats say.

Whether the international community will come up with the money this time is uncertain. "It would be terribly unfortunate if it were not. That means that we don't learn" said one senior UN official close to the talks. "Last time around it was exactly like this, there was a great deal of interest and as soon as the Russians went, people forgot about Afghanistan and this is the result".