U.N. Secretary General Ban Ki-moon has expressed doubts about European plans to destroy migrant smuggler boats and says the focus should be on saving lives at sea.

Ban told reporters in Brussels on Wednesday that "the priority should be given to life saving and strengthening search and rescue."

More than 80,000 people have crossed the Mediterranean in search of better lives in Europe so far this year. More than 1,800 are feared to have died.

Destroying the boats that bring them over is one strand of the European Union's plan to "disrupt the business model" of smugglers.

Ban was also cool on an EU security operation that could hunt down smugglers in Libyan territorial waters.

"We need to address all of this in a comprehensive way," he said.