More than 63,000 migrants who applied for European Union asylum claimed to be unaccompanied minors in 2016.
The figure, released by the EU's statistical agency, revealed that of the tens of thousands to enter Europe last year, two thirds said they were 16 or 17-year-old men.
More than half of the 63,000 flooding into mainland Europe to flee war in their home nations came from Afghanistan and Syria.
Eurostat said Thursday unaccompanied minors applied for international protection in the 28 EU nations as well as Iceland, Liechtenstein, Norway and Switzerland.
It said the number was a third down from the previous year but still five times higher than the annual average.
More than two thirds of the minors were said to be males and aged 16 to 17, almost 6,300 were under 14 and nearly 60 percent of the applicants sought asylum in Germany.
As well as the Middle East, migrants are travelling from North Africa in an attempt to escape conflict.
In the Mediterranean Sea, Libya's coastguard said it had intercepted nearly 500 people packed onto a wooden boat and returned them to Tripoli on Wednesday after warning off a ship preparing to pick them up for passage to Europe.
Most migrants attempt the perilous journey on flimsy inflatable boats provided by smugglers that are barely equipped to make it to international waters.
Larger wooden boats carrying several hundred migrants are rarer, but are still regularly seen in the treacherous stretch of water between the two continents.
A refugee raises a child into the air as Syrian and Afghan refugees are seen on and around a dinghy that deflated
Some migrants are turned back by the Libyan coastguard, which generally delivers them to detention centres notorious for poor conditions and ill-treatment.
The coastguard is receiving training from the European Union as it seeks to limit migrant departures and deaths.
Other migrants are taken to Italy after being picked up by NGO ships that run rescue missions, European or Italian naval and coastguard patrols, and other international vessels.
Qassem said the wooden boat intercepted on Wednesday was carrying nearly 300 Moroccans, 145 Bangladeshis, 23 Tunisians, and other migrants from elsewhere in Africa and the Middle East.
Those on board said they had left the western Libyan city of Sabratha on Tuesday night.
There were about 20 women, some five of whom were being taken for medical treatment as they arrived in Tripoli and one appeared to be seriously ill.
One 24-year-old Moroccan man said he had come to Libya five weeks earlier in order to try to reach Europe.
A 28-year-old man, also Moroccan, said he had been working in Libya for four years, but had decided to leave because the situation was deteriorating.
A Syrian woman on board said she had travelled through six countries to reach Libya, paying $1,000 in each and leaving two sons aged 12 and 13 behind in Jordan.
'I wanted to leave for Europe,' she said. 'It was an attempt to get a better life and reunite my whole family in Europe, but unfortunately we couldn't make it.'
Illegal immigrants, who were rescued by the Libyan coastguard in the Mediterranean off the Libyan coast, arrive at a naval base in the capital Tripoli on May 10, 2017
Migrants gesture towards members of Proactiva Open Arms NGO as they wait to be rescued
Young men leaning over the edge of a boat a it pulls into a dock in Salerno in Italy
Illegal immigrants, who were rescued by the Libyan coastguard in the Mediterranean off the Libyan coast, arrive at a naval base in the capital Tripoli on May 10
Meanwhile, an Italian prosecutor said on Wednesday he is investigating some members of humanitarian organisations rescuing migrants in the Mediterranean Sea on suspicion they may have cooperated with people smugglers.
Ambrogio Cartosio, chief prosecutor of the western Sicilian city of Trapani, told a parliamentary committee in Rome that the organisations themselves were not a target of the inquiry.
Suspicions arose because some rescue crew seemed to know in advance where to find the flimsy boats crowded with migrants after smugglers sent them off from north African ports, he said.
Some Italian politicians have claimed non-governmental organisations (NGOs) run a taxi service bringing migrants to Italy.
'We understand that NGOs made some rescues at sea without informing the Coast Guard,' Cartosio said.
Italy's Coast Guard is in charge of coordinating all rescues in international waters off the shores of Libya and aid groups have strongly denied any ties to human traffickers.
