London, England (CNN) -- London's two major airports were closed Monday as a cloud of ash from a volcano in Iceland moved east into England, British air authorities said. All flights into and out of Heathrow and Gatwick airports have been canceled for a six-hour period beginning early Monday, airport officials said. The affected flights are those scheduled between 1 a.m. (8 p.m. Sunday ET) and 7 a.m. (2 a.m. ET). The Monday cancellations were the latest in a round of weekend closures of airports across the United Kingdom and into continental Europe. Amsterdam's Schipol Airport announced it would be closed Monday from 6 a.m. to 2 p.m. (midnight Sunday to 8 a.m. ET), according to an airport spokeswoman, who said officials were waiting on guidance from air authorities to decide when flights will resume.
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NEW: Amsterdam's Schipol Airport to close Monday from 6 a.m. to 2 p.m.
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Affected flights for Gatwick and Heathrow are scheduled between 1 a.m. and 7 a.m.
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Three of Ireland's airports also affected, as well as Manchester and Liverpool
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Problems started in April after eruption of volcano beneath the Eyjafjallajokull glacier
International flights through @placeholder airspace will not be affected, it said.