Youth unemployment across the world has climbed to a new high and is likely to climb further this year, a United Nations agency said Thursday, while warning of a “lost generation” as more young people give up the search for work. 　　The agency, the International Labor Organization, said in a report that of some 620 million young people ages 15 to 24 in the work force, about 81 million were unemployed at the end of 2009—the highest level in two decades of record-keeping by the organization, which is based in Geneva. 　　“There’s never been an increase of this magnitude — both in terms of the rate and the level — since we’ve been tracking the data,” said Steven Kapsos, an economist with the organization. The agency forecast that the global youth unemployment rate would continue to increase through 2010, to 13.1 percent, as the effects of the economic downturn continue. It should then decline to 12.7 percent in 2011. 　　In some especially strained European countries, including Spain and Britain, many young people have become discouraged and given up the job hunt, it said. The trend will have “significant consequences for young people,” as more and more join the ranks of the already unemployed, it said. That has the potential to create a “‘lost generation’ comprised of young people who have dropped out of the labor market, having lost all hope of being able to work for a decent living.” 　　The report studied the German, British, Spanish and Estonian labor markets and found that Germany had been most successful in bringing down long-term youth unemployment. In Spain and Britain, increases in unemployment were particularly pronounced for those with lower education levels. 　　Data from Eurostat, the European Union’s statistical agency, show Spain had a jobless rate of 40.5 percent in May for people under 25. That was the highest level among the 27 members of the European Union, far greater than the 9.4 percent in Germany in May and 19.7 percent in Britain in March.