Hundreds of flights grounded as ash cloud reaches Britain *

LONDON, May 24 (agencies): Airlines halted hundreds of flights Tuesday after a plume of ash from an erupting volcano in Iceland blew over Britain, even forcing US President Barack Obama to revise his travel plans. Barely a year after a similar eruption in Iceland forced the biggest closure of European airspace since World War II, Britain's flagship carrier British Airways was the first to suspend flights from London to Scotland. Dutch airline KLM, Irish carrier Aer Lingus and budget airline Easyjet then followed suit, and Britain's NATS air traffic control also warned of disruption to airports in northern England, including Newcastle, and Northern Ireland. "Most airlines have cancelled flights today -- 252 flights," said Brian Flynn, head of operations at the Brussels-based Eurocontrol. In a Twitter update, he warned that the ash cloud "will continue possibly southwards to France and Spain but hard to say now because (weather) forecasts are not precise for the end of the week." He said that by the end of the day, the cloud "will cover southern parts of Scandinavia, Denmark and northern parts of Germany possibly." This could threaten planning for events ranging from the G8 summit to the Champions League final between Barcelona and Manchester United to take place at London's Wembley Stadium on Saturday. Spanish giants Barcelona said they would make a decision Tuesday regarding their travel plans. The ash cloud reached Norway on Tuesday morning, a spokesman for airport operator Avinor told AFP, adding that the disruption so far was "very small".