LONDON - A lingering volcanic ash plume forced extended no-fly restrictions over much of Europe Saturday, as Icelandic scientists warned that volcanic activity had increased and showed no sign of abating ��" a portent of more travel chaos to come. Although the ash plume has grown, a northerly wind was expected to allow enough visibility for scientists to fly over the volcano Saturday. Scientists want to see how much ice has melted to determine how much longer the eruption could spew ash. Because the volcano is situated below a glacial ice cap, the magma is being cooled quickly, causing explosions and plumes of grit that can be catastrophic to plane engines if prevailing winds are right. "The activity has been quite vigorous overnight, causing the eruption column to grow," Icelandic geologist Magnus Tumi Gudmundsson told The Associated Press on Saturday. "It's the magma mixing with the water that creates the explosivity. Unfortunately, there doesn't seem to be an end in sight." An expansive cloud of grit hovered over parts of western Europe on Saturday, triggering extended flight bans that seemed likely to disrupt world leaders' plans to attend Sunday's state funeral for Polish President Lech Kaczynski and his wife Maria in the southern city of Krakow. South Korean Prime Minister Chung Un-chan was the first to announce he was canceling his trip to Poland, while President Barack Obama, Russian President Dmitry Medvedev and German Chancellor Angela Merkel still planned to attend. Kaczynski's family has said they want the funeral to go ahead as planned. Aviation experts say the volcanic plume has caused the worst travel disruption Europe ��" and the world ��" has ever seen. On Saturday, British and German officials extended their closure of airspace until at least 0000 GMT (8 p.m. EDT). The Belgian, French and Swiss governments extended their ban until Saturday evening. Italian aviation authorities were closing airspace in northern Italy on Saturday until midday (1000 GMT; 6 a.m. EDT), with airports in Milan and Venice to close.
