As the war in Afghanistan unfolds, there is frantic diplomatic activity to ensure that any post-Taliban government will be both democratic and pro-west. Hidden in this explosive geo-political equation is the sensitive issue of securing control and export of the region's vast oil and gas reserves.

The Soviets estimated Afghanistan's proven and probable natural gas reserves at 5 trillion cubic feet - enough for the UK's requirement for two years - but this remains largely untapped because of the country's civil war and poor pipeline infrastructure.

More importantly, according to the US government, "Afghanistan's significance from an energy standpoint stems from its geographical position as a potential transit route for oil and natural gas exports from central Asia to the Arabian Sea".

To the north of Afghanistan lies the Caspian and central Asian region, one of the world's last great frontiers for the oil industry due to its tremendous untapped reserves. The US government believes that total oil reserves could be 270bn barrels. Total gas reserves could be 576 trillion cubic feet. These dwarf the UK's proven reserves of 5bn barrels of oil and 27 trillion cubic feet of natural gas.

The reason oil is so attractive to the US - which imports half of its oil - and the west, is for three reasons. "Firstly it is non-Opec oil," says James Marriott, an oil expert from Platform, an environmental NGO. "Opec has been the bête-noire of the west since its inception in 1960. Secondly, these states are not within the Arab world and thirdly, although they are Muslim, they are heavily secularised."

The presence of these oil reserves and the possibility of their export raises new strategic concerns for the US and other western industrial powers. "As oil companies build oil pipelines from the Caucasus and central Asia to supply Japan and the west, these strategic concerns gain military implications,"argued an article in the Military Review, the Journal of the US army, earlier in the year.

Despite this, host governments and western oil companies have been rushing to get in on the act. Kazakhstan, it is believed, could earn $700bn (£486bn) from offshore oil and gas fields over the next 40 years. Both American and British oil companies have struck black gold. In April 1993, Chevron concluded a $20bn joint venture to develop the Tengiz oil field, with 6-9bn barrels of estimated oil reserves in Kazakhstan alone. The following year, in what was described as "the deal of the century", AIOC, an international consortium of companies led by BP, signed an $8bn deal to exploit reserves estimated at 3-5bn barrels in Azerbaijan.

The oil industry has long been trying to find a way to bring the oil and gas to market. This frustration was evident in the submission by oil company Unocal's vice-president John Maresca, before the US House of Representatives in 1998. "Central Asia is isolated. Their natural resources are landlocked, both geographically and politically. Each of the countries in the Caucasus and central Asia faces difficult political challenges. Some have unsettled wars or latent conflicts."

The industry has been looking at different routes. The Caspian Pipeline Consortium (CPC) route is 1,000 miles west from Tengiz in Kazakhstan to the Russian Black Sea port of Novorossiisk and came on stream last week. Oil will go by tanker through the Bosporus to the Mediterranean. Another route being considered by AIOC goes from Baku through Tbilisi in Georgia to Ceyhan in Turkey. However, parts of the route are seen as politically unstable as it goes through the Kurdistan region of Turkey and its $3bn price tag is prohibitively expensive.

But even if these pipelines are built, they would not be enough to exploit the region's vast oil and gas reserves. Nor crucially would they have the capacity to move oil to where it is really needed, the growing markets of Asia. Other export pipelines must therefore be built. One option is to go east across China, but at 3,000km it is seen as too long. Another option is through Iran, but US companies are banned due to American sanctions. The only other possible route is through Afghanistan to Pakistan. This is seen as being advantageous as it is close to the Asian markets.

Unocal, the US company with a controversial history of investment in Burma, has been trying to secure the Afghan route. To be viable Unocal has made it clear that "construction of the pipeline cannot begin until a recognised government is in place in Kabul that has the confidence of governments, lenders, and our company."

This, it can be argued, is precisely what Washington is now trying to do. "Washington's attitude towards the Taliban has been, in large part, a function of oil," argues Steve Kretzmann, from the Institute for Policy Studies in the US. "Before 1997, Washington refused to criticise and isolate the Taliban because Kabul seemed to favour Unocal, to build a proposed natural gas pipeline from Turkmenistan through Afghanistan to the Pakistan coast."

In 1997, the Taliban signed an agreement that would allow a proposed 890-mile, $2bn natural gas pipeline project called Centgas led by Unocal to proceed. However by December 1998, Unocal had pulled out citing turmoil in Afghanistan making the project too risky.

To secure stability for the Afghan pipeline route, the US State Department and Pakistan's intelligence service funnelled arms to the Taliban, argues Ahmed Rashid in his book: Taliban: Militant Islam, Oil and Fundamentalism in Central Asia, the book Tony Blair has been reportedly reading since the conflict started. Rashid called the struggle for control of post-Soviet central Asia "the new Great Game".

Critics of the industry argue that so long as this game is dependent on fossil fuels the region will remain impoverished due to the effects of the oil industry, which is, says Kretzmann, "essentially a neo-colonial set-up that extracts wealth from a region. The industry is sowing the seeds of poverty and terrorism. True security, for all of us, can only be achieved by reducing our dependence on oil."