(Polished diamond exports earned $5.2 billion last year.)

However, Botswana's terms of trade improved because higher prices for oil imports were more than offset by higher prices for diamond exports.

For countries economically dependent on diamond exports, this can be a substantial punishment, as it disallows trade with much of the rest of the world.

Demand for port access also declined in the 1970s as the volume of diamond exports decreased.

One Million Workers India's diamond exports amounted to only $39 million worth of polished diamonds in 1970, compared with the $3.5 billion last year.

Mogae also warned that Botswana could not continue to depend on diamond exports.

Antwerp is the number one diamond market in the world, diamond exports account for roughly 1/10 of Belgian exports.

The UN voted to lift a ban on diamond exports, which fuelled the civil war, in April 2007.

The other two would impose an embargo on arms sales and diamond exports and enlarge the United Nations peacekeeping force and strengthen its powers.

Due largely to its diamond exports, Botswana had about £1.2 billion in foreign currency reserves in 1989.