Balkan countries at the front line of the migrant crisis say they could close their borders to avoid becoming buffer zones for new arrivals. Bulgaria said it, Romania and Serbia would act if states further north, which migrants hope to reach, close their doors. The threat comes ahead of talks between Balkan states and EU members in Brussels. Slovenia's president said his country would "act on its own before it is too late" if no solution was reached. Prime Minister Miro Cerar had previously refused to rule out building a fence along its border with Croatia. The International Organization for Migration said that more than 9,000 migrants arrived in Greece every day last week - the highest rate so far this year. Most of the migrants - including many refugees from the conflicts in Syria, Iraq and Afghanistan - want to reach Germany to claim asylum.