Sudan cut diplomatic ties on Sunday, accusing its western neighbor of helping train rebels who attacked a suburb of Khartoum, Sudan's capital, over the weekend.

Abdalmahmood Abdalhaleem Mohamed, Sudan's ambassador to the United Nations, told reporters that he expected the Security Council, and especially its permanent members, to "use their leverage on Chad."

Mohamed likened Saturday's attack by hundreds of Justice and Equality Movement (JEM) rebels on the suburb of Omdurman to the attacks on New York and Washington on September 11, 2001.

UN Secretary-General Ban Ki-moon issued a statement through his spokesman expressing "grave concern" over the attack and continued fighting.

The Security Council is scheduled on Tuesday to discuss Sudan's Darfur region, where at least 200,000 people have died and another 2.5 million have been displaced since ethnic African tribesmen took up arms against the Arab-dominated government five years ago.