The North Atlantic Treaty Organisation alliance is to be more deeply involved from this coming August in boosting the security of Afghanistan, British officials in London have revealed.

This is the first time that NATO has been deployed away from its traditional area of operations -- Western Europe and the North American continent -- and the move reflects the American determination to prevent the revival of Al Qaeda-supported Islamic militancy in Afghanistan.

British officials, who chose the occasion of Afghan President Hamid Karzai's state visit to the United Kingdom to announce the enhanced role of NATO, have stressed that the alliance will underpin the activities of the United Nations-mandated International Security Assistance Force that currently operates in Afghanistan.

The officials said NATO's expanded role is not intended to threaten Iran, which already has to contend with the presence of US and British forces on its western flanks in Iraq.

"It should not worry Iran unless you are a conspiracy theorist," one British official said.

Foreign diplomats stationed in London pointed out that at the recent G-8 summit Teheran was warned not to develop nuclear weapons technology.

The latest warning, coupled with increased US and British military activities along Iran's borders with Iraq and Afghanistan, is bound to worry the authorities in Teheran, the diplomats said.

NATO is also expected to support the deployment of eight Provincial Reconstruction Teams, made up of both civil and military experts, that will try and extend the authority of the Karzai administration beyond the borders of Kabul.

Although security issues are expected to dominate Karzai's discussions with British officials during his three-day state visit, which includes an audience with Queen Elizabeth II, the Afghan president is also expected to press for more economic assistance from the UK and other countries.

Last year Afghanistan received some £1.8 billion in foreign aid, less than what was promised at an earlier meeting of donor countries in Tokyo.

Afghan officials accompanying Karzai have explained that more money is needed for day-to-day expenditure, including the payment of civil servants and teachers' salaries, as well as for longer-term projects such as roads, housing and the eradication of heroin producing poppies.

Funds will also be needed for this coming October's conference to agree a new constitution for the country, as well as for next year's national elections. Before leaving the UK next Friday, Karzai will also deliver a lecture at St Anthony's College in Oxford.