JAKARTA - Police in the Indonesian capital Jakarta have banned a rally organized by Islamist groups ahead of next week's hotly contested election to lead the city, officials said on Tuesday.The rally on Feb. 11, just four days before voting day, would have been the latest in a series of mass demonstrations by Muslims against the incumbent governor, a Christian, who they claim insulted the Koran.The protests, led by hardline groups and attended by hundreds of thousands of people, have raised fears of creeping religious intolerance and political instability in the world's third-largest democracy and most populous Muslim nation.Police said they last week had received notice of the rally from the organizers, a large group of Islamic organizations led by hardliners like the Islamic Defenders Front (FPI)."Police will not allow it," said Jakarta police spokesman Argo Yuwono, without elaborating.Earlier in the day, national police chief Tito Karnavian told media that the rally was suspected to be political in nature and came too close to the quiet period when all candidates and their supporters are required to stop canvassing. Feb. 11 is the last day when campaigning is permitted.Indonesian law guarantees freedom of assembly. Police did not say what the punishment would be for violating the ban on Saturday's rally.One protest organizer called on police to explain why they rally had been banned."The police need to clarify what the danger is, if they say there is any," said FPI spokesman Slamet Maarif.Jakarta's first ethnic Chinese and Christian governor, Basuki Tjahaja Purnama, is currently being tried on blasphemy charges that many see as unfair and politically motivated. He remains a front runner in the race to lead the city of over 10 million people.His main rival is Agus Yudhoyono, son of former president Susilo Bambang Yudhoyono, and a Muslim.