More than 22,000 passengers and 209 flights affected, especially those bound to and from Singapore, after eruption of Anak KrakatoaIndonesia halted operations at its main international airport on Sunday due to an ash cloud from the Anak Krakatoa volcano.Anak Krakatoa erupted on Saturday, producing lava and booming sounds that could be heard up to 700km away (435 miles), Indonesias geology agency said.