German Chancellor Angela Merkel said on Thursday she was "optimistic" but cautious on reaching a crucial deal with Turkey to halt the flood of migrants coming to Europe.

German Chancellor Angela Merkel said on Thursday she was "optimistic" but cautious on reaching a crucial deal with Turkey to halt the flood of migrants coming to Europe.

"There are still complicated talks ahead but the fundamental direction is clear. I share the view of the European Council president (Donald Tusk) who spoke of cautious optimism, stressing the word cautious," Merkel said as she arrived for a crunch two-day EU leaders' summit in Brussels.