While the world's attention is gripped by unfolding plans for US action against Afghanistan's Taliban regime, more discreet diplomatic focus is turning on Rome, and a man who might play a crucial role.

Some Afghanistan experts say that if the Taliban regime is toppled, Mohammed Zahir Shah, the 86-year old former Afghan king, could be a central figure in a transitional administration.

Since being ousted in a coup in 1973, Zahir Shah has been living in the suburbs of the Italian capital, waiting for a chance to return to the country he ruled for 40 years.

Following the terrorist attacks on New York and Washington, he has been courted by senior diplomats from numerous governments and organisations, all of them pondering what role he might play in a post-Taliban Afghanistan.

Last Sunday, Francesc Vendrell, the United Nations envoy for Afghanistan, visited the normally reclusive ex-king in Rome, where he lives in a gated community amid sports stars and celebrities.

On Tuesday, William Pope, the US charge d'affaires in Rome, made a similar visit. This weekend, the pace will quicken when figures from the anti-Taliban Northern Alliance are expected in Rome for a meeting with the former king.

Over the last two years, four countries - the US, Italy, Iran and Germany - have been in the vanguard of diplomatic activity regarding Afghanistan. The four states are members of a UN-sponsored contact group in Geneva - the so-called "Geneva Initiative" - which is in regular touch with anti-Taliban rebels.

A senior Italian diplomat said on Wednesday the contact group was being careful not to promote the idea of replacing the Taliban regime in Kabul with a monarchy. "We have good reason to think the king is a highly popular figure in Afghanistan and that he could be a point of reference in the future," said the diplomat.

"He could successfully convene a loya jirga - a kind of grand assembly - of the country's tribes. But whatever happens, it would ultimately be up to the assembly to decide what kind of government should replace the Taliban regime."

Born in 1914 and educated in Paris and Kabul, Zahir Shah, who is fluent in French, Italian, English and Pashto, became king shortly after the assassination of his father in 1933. He was 19 and the latest in the Durrani dynasty that conquered the throne of Kabul in 1761.

Diplomats who support a role for him if the Taliban is toppled, point out that he did much to democratise Afhganistan, approving a new constitution and freeing the press as well allowing parliamentary elections.

In 1973 a medical trip to Rome turned into a nearly three-decade-long exile when Zahir Shah's cousin, and one-time prime minister, overthrew his relative, sparking instability that would eventually destroy Afghanistan and uproot millions of its citizens, propelling them into poverty and starvation.

Zahir Shah's popularity is largely based on the fact the Durranis are from the Pashtun ethnic group, based in the south of the country and comprising the majority of Afgh an nationals. By contrast, the Northern Alliance is made up of Tajiks and Uzbeks who are traditionally hostile to the Pashtuns.

However, Rome-based diplomats believe the visit by the Northern Alliance this weekend could emerge as an important moment of reconciliation.

They say the recent assassination of Ahmed Shah Massoud, the charismatic leader of the Northern Alliance, may be one reason why the alliance's leaders are now prepared to take this step.

In Iran, however, there are signs that Afghanistan's tribes are highly fragmented and that the king is far from being a universally admired figure.

Mohammad Khair Khah, "ambassador" for the Northern Alliance in Iran and a member of the mainly Tajik Jamiat-e Islami, said one man could not rule over Afghanistan, but that Zahir Shah could play a role in forming a future government.

But Yusef Vaeizi, the representative in Iran of the Shia Hezb-e Wahdat tribe, denounced the former king as a liberal and a puppet of the US who should have no role in a future government.

"He only watched while Afghanistan was divided," Mr Vaeizi, a cleric trained in Iran, said. He recognised the need for the Pashtuns to be represented in a future broad-based government, but said the former king must be ruled out. Afghanistan's neighbours also have their doubts about restoring the ex-king, according to Rasul Amin, an Afghan intellectual in exile in Pakistan.

"Pakistan would see a government run by Zahir Shah as too independent and too popular with its own Pashtun population," he said in a recent interview with Italian news agencies.

"Iran would fear that his return would bring back memories of the Pahlavi monarchy that was overthrown in 1979. And Saudi Arabia would see the end of the influence it has exercised by financing the "Madrasa" - the Koran-based schools attended by thousands of Afghan students."

For his part, the octagonarian king, who is said to be in good health and married with six children and several grandchildren, has signalled he would be willing to give up his reclusive but comfortable life in Italy to serve his people in Afghanistan.

Additional reporting by FT.com staff