By Hadeel Al Shalchi

CAIRO, Nov 6 (Reuters) - Egypt's Muslim Brotherhood failed in an attempt on Wednesday to overturn a court ruling banning it, the state news agency said, another blow to the debilitated Islamist movement.

A court in September outlawed the Brotherhood after the army overthrew President Mohamed Mursi in July following mass protests against his rule.

The case against his Brotherhood was brought by a lawyer from the leftist Tagammu party, which cited the need to protect Egyptians from violence.

It accompanied a campaign by security forces to crush the Islamist movement in which hundreds of its members have been killed, thousands arrested, and its leaders, including Mursi, put on trial.

Wednesday's decision was another political blow to the group.

"In its scheduled session today, the Cairo Urgent Cases court dismissed an appeal raised by the Muslim Brotherhood to stop the execution of the previous order banning the activities of the group," state news agency MENA reported.

Since Mursi's overthrow Egypt has become fiercely divided, with state media lionising the military and police for the crackdown and his supporters frequently protesting in the streets.

The military-installed government has promised new elections next year which foreign governments say must include all political factions to mark a credible return to democracy. The court ruling indicated the Brotherhood was likely to be excluded.

Mursi, Egypt's first freely elected president, faces charges of inciting violence. His trial began on Monday and was adjourned by a judge to early January. (Reporting by Hadeel Al-Shalchi; Editing by Yara Bayoumy and Angus MacSwan)