Millions of stranded travelers face further air chaos as the volcanic ash from Iceland that has closed most of Europe's airspace continues to spread. Estimated three-quarters of flights were cancelled yesterday. About 20 countries closed their airspace – some have extended flight bans into tomorrow. Scientists say, the Icelandic volcano activity shows no sign of abating. The large no-fly zone also means that some world leaders will not be attending the funeral of the Polish president today. US President Barack Obama has cancelled his visit to Poland. Southern Iceland's Eyjafjallajokull volcano began erupting for the second time in a month on Wednesday, sending a plume of ash 8.5 kilometres high into the air. Iceland lies on the Mid-Atlantic Ridge, the highly volatile boundary between the Eurasian and North American continental plates.<br/>