Senior separatist leaders Syed Ali Geelani and Mirwaiz Umer Farooq on Saturday defied house arrest and staged a sit-in outside their residences as part of a separatist-called 'referendum march' in Srinagar.Both Geelani and Mirwaiz were later arrested and placed under house arrest.The separatists had called for a referendum rally to city centre Lal Chowk on Saturday asking people to march or squat on the ground till Sunday evening if intercepted by the security forces.The authorities had sealed Lal Chowk, disallowing all pedestrian and vehicular movement towards the city centre.Coils of razor fitted concertina wire were placed on all roads leading to Lal Chowk and all lanes and by lanes leading to the city centre were manned by security forces wearing full riot gear.