* Protesters demand withdrawal of proposal to protect army
* Failure to resolve dispute could impact Nov. 28 ballot
* Rival Islamist groups in unified call against army
By Marwa Awad
CAIRO, Nov 18 (Reuters) - Over 50,000 Egyptian protesters flocked to Cairo's Tahrir square on Friday to pressure the military government to transfer power to elected civilian rule, after the cabinet tried to enshrine the army's role in a constitutional proposal.
The protesters, mostly bearded men and veiled women, sang religious chants before Friday prayers while others handed out flyers demanding the withdrawal of the constitutional proposal and presidential elections be held no later than April 2012.
"Does the government want to humiliate the people? The people revolted against Mubarak and they will revolt against the constitution they want to impose on us," a member of an orthodox Islamic Salafi group cried out over loud speakers, to the cheers of thousands of protesters.
The mass rally recalled the demonstrations in Tahrir square during the 18-day bloody uprising that toppled President Hosni Mubarak on Feb. 18.
Parliamentary elections on Nov. 28 could be disrupted if political parties and the government fail to resolve a dispute over proposed articles that shield the army from oversight in parliament, potentially allowing it to defy an elected government.
Over 39 political parties and groups said in a joint statement they would rally "to protect democracy and the transfer of power" after negotiations broke down between Islamist groups and the cabinet.
Salafi parties and movements, who follow orthodox Islamic teachings, were the earliest to galvanise support for the Friday protest, with the Muslim Brotherhood and a number of liberal parties following suit.
Thousands of Salafi protesters arrived in Cairo from different parts of the country, many waving flags and singing the national anthem.
"We came by bus from the Delta. We have been called to come and show our refusal of army rule and support of civilian rule," said Mohamed Ali, a member of the Salafi Al-Asalah party.
In the port city of Alexandria, thousands of Islamists and youth groups also held a mass rally and planned to head to a military base in a show of protest against the army.
"We went down to demand change but they removed Mubarak and brought the Field Marshal," protesters in Alexandria chanted.
Deputy Prime Minister Ali al-Silmi showed a constitutional draft to political groups earlier this month which would give the army exclusive authority over its internal affairs and budget.
Despite the unified call against the ruling generals, Tahrir square was split between the Muslim Brotherhood's Freedom and Justice Party and their Salafi rivals, represented by several political parties.
The Islamist rivals set up separate sound stages and organised their own speeches and chants, only joining forces for Friday prayers.
"Our aims are one but there are differences between us as Islamist groups," said Abdullah Galil, a Salafi youth.
Liberal and leftist parties were also marching to Tahrir to take part in the rally.
"There is no alternative but a return to the demands of the revolution which we must put back on track through a unified political voice," Mohamed Anis, co-founder of the liberal mainstream Justice Party said. (Writing by Marwa Awad; Additional reporting by AbdelRahman Mansour in Alexandria; Editing by Sophie Hares)