Mr Bush's warning provoked a harsh response from Iran

The Americans are clearly keen to maintain the pressure on Iran as the interim government here tries to strengthen its grip on the country.

Historically, the neighbours have backed different factions during Afghanistan's conflicts of the past two decades and this has only added to the country's problems.

It is not just the Americans who have warned that disaster could befall the fledgling new administration if this were to happen again now.

US warning

The US envoy, Afghan-born Zalmay Khalilzad, told journalists in Kabul that the US would consider that Iran was meddling in Afghanistan if it armed or funded local groups without the knowledge of the new authorities.

He also warned Iran against sending elements from its own Revolutionary Guards or Afghans it has trained and who are members of the group known as Mohammed Soldiers.

Afghan leader Hamid Karzai has described Iran as a "friendly country"

Mr Khalilzad said he thought there was reason to be concerned about all of these, without elaborating.

He also said he believed the Iranians had some al-Qaeda members in their possession but he said they had not made them available to the United States.

Iran insisted in response to President Bush's earlier warnings that it was not stirring up trouble in Afghanistan.

But the Iranian Government will be under more pressure to support a durable peace in Afghanistan when the United Nations Secretary General, Kofi Annan, visits Tehran next week, after the Afghanistan aid conference in Japan.