Thousands of supporters of Nepal's Maoist former rebels attended a rally in the capital on Sunday to press their demands for the abolition of the monarchy. Carrying banners and shouting slogans, the activists brought traffic to a halt as they marched through the streets and gathered in a public area in the heart of the hill-ringed capital. The Maoists plunged the Himalayan country into turmoil early this month. when they withdrew from the coalition government.