By Foo Yun Chee STRASBOURG (Reuters) - "Alarming" numbers of migrants are reaching Libya to cross the Mediterranean, a senior EU official said on Wednesday, adding a warning that Italy must be ready for them to avoid new border chaos inside Europe. "The numbers of would-be migrants in Libya are alarming," European Council President Donald Tusk told the European Parliament a day after Austria said it planned tighter controls on its Italian border in anticipation of a summer migrant surge. Noting that anarchy in Libya ruled out for now the kind of deal made with Turkey to block what was last year's main route into Europe via Greece, Tusk said EU allies must be ready to help manage new arrivals within Italy, as well as on Malta.