The leaders of France, Germany, Italy and Balkan nations are meeting to better prevent extremists from sneaking in with migrants who are moving west across Europe.

German Chancellor Angela Merkel, French President Francois Hollande, Italian Prime Minister Matteo Renzi will also discuss boosting opportunities for youths from countries that dream of joining the 28-nation European Union.

The meetings Monday of leaders, diplomats and finance ministers in Paris come amid questions over the EU's future after Britain voted to leave. Balkan nations that suffered through wars and political breakups in the 1990s worry that they will now face more hurdles to their membership bids as the EU struggles to stay together.

On top of the agenda is reinforcing security checks of migrants traversing the Balkans toward Western Europe.