By Martin Plaut BBC, London

A report by an American-based think tank predicts the war in the Sudan could escalate with both the government and rebels buying new weapons.

The International Crisis Group's (ICG) report comes as the Sudanese Government and the Sudan People's Liberation Army (SPLA) are engaged in peace talks in Kenya.

The MiGs could be used to deter the rebels from extending the war

The Sudanese Government is enjoying substantially enhanced revenues from the oil it is pumping from southern Sudan.

According to the new report, this cash is now being used to purchase Russian MiG-29s.

The ICG report was written by John Prendergast, who served as African expert on the National Security Council under US President Bill Clinton.

Sudan's civil war has entered its most destructive phase to date

ICG report

News of the purchase first emerged in May when a Russian report suggested Sudan had placed a $120m order for the MiGs.

The aircraft could be used to prevent rebels of the SPLA from re-supplying their forces from the air, although experts are divided on exactly how effective these aircraft would be in shooting down slow-flying jets used by the rebels.

But the MiGs are multi-role fighters and, if they come with Russian or Ukrainian pilots, could be used to attack targets on the ground with rockets or bombs.

Sudan's neighbours will be also be worried by this development.

Mr Prendergast says the SPLA and its allies have around 10,000 troops on the Eritrean border.

The new aircraft could be used to deter the SPLA from extending the current conflict to northern Sudan.

The report calls on the United States to use its diplomatic muscle to prevent the current peace talks from floundering.