Sudan cut diplomatic relations with Chad on Sunday after an attack on Khartoum by Darfur rebels which it said was supported by Chadian President Idriss Deby.

The rebels fought Sudanese troops in a suburb of Khartoum on Saturday in a bid to seize power. Officials said the attack was defeated, but it was the first time in decades of conflict that rebels had brought their battle to the capital.

"These forces are all basically Chadian forces supported and prepared by Chad," President Omar Hassan al-Bashir said on state television.

"...We are now cutting our diplomatic relations with this regime."    

Bashir said the fighters, who made a lightning advance across 600 km (400 miles) of desert and scrub to attack a western suburb of Khartoum, were led by Khalil Ibrahim of the Darfur rebel Justice and Equality Movement (JEM).

Chad has denied involvement but analysts say it may have backed the JEM rebels to retaliate for an attack on the Chadian capital three months ago.

"It seems that at least in part this is payback for the NCP's (Sudan's ruling party) support for rebels in Chad who almost toppled the government there in February," said Amjad Atallah from the Save Darfur Coalition.

Rebels in the south and west of Sudan, Africa's biggest country, have for decades complained of neglect by the Arab-dominated central government.

A peace deal between north and south ended one civil war in 2005 and boosted Sudan's economy by increasing oil production in the south, but that agreement did not cover the conflict that erupted in Darfur five years ago.

International experts estimate some 200,000 people have died and 2.5 million been made homeless in Darfur since mostly non-Arab rebels took up arms. -Reuters