Greece’s national Olympic committee said Wednesday that using a former velodrome in Athens to temporarily shelter thousands of refugees would cause competitive cycling to “completely wither” in the country.

The committee said Wednesday that all available sporting venues are "absolutely necessary" to help Greek athletes prepare for the 2016 Olympic Games in Rio. It said the velodrome is the only available racing venue in the country.

The government has not confirmed press reports that it wants to house refugees in the velodrome. Several disused former Olympic venues in Athens are being used to temporarily shelter migrants, more than 600,000 of whom have reached Greece this year.

The temporary housing refusal came as authorities Wednesday cracked down on refugee smuggling rings across Europe.

France said police have detained eight people accused of being involved in a smuggling ring that brings refugees to Britain by rubber boat from the northern French city of Dunkirk.

Thousands fleeing war and poverty have gathered around the French port cities of Calais, Dunkirk and others in hopes of sneaking across the English Channel in ferries or undersea trains to Britain. More than a dozen have died this year attempting the dangerous journey.

Interior Minister Bernard Cazeneuve said Wednesday that smugglers were charging up to $13,100 for the trip across the Channel.

Cazeneuve said French authorities have dismantled 200 smuggling networks and detained more than 3,000 people so far this year in investigating human trafficking networks.

He said French-British cooperation against illegal migration has been reinforced since he met Monday with British Home Secretary Theresa May.

In Cyprus, police said a court ordered three men held for eight days on suspicion of people smuggling after crews rescued 26 people on a boat in trouble off the Mediterranean island's southeastern tip.

Police spokesman Andreas Angelides told The Associated Press on Wednesday that the men — aged 30, 48 and 35 — are being investigated on charges of helping refugees enter Cyprus illegally and of conspiracy to commit a crime.

Angelides said each of 26 people — including 13 children — had paid $1,000 to board the boat, which is believed to have left Friday from Tripoli, Lebanon.

Rough seas and strong winds hampered the rescue operation late Tuesday, but authorities believe all on the boat were saved.

Germany's federal police also are conducting raids against international human trafficking networks across Germany. More than 500 officers were conducting searches of 24 homes in the states of North Rhine-Westphalia, Lower Saxony and Baden-Wuerttemberg.

A federal police spokesman said Wednesday they were targeting "criminal, internationally operating trafficking groups." The spokesman, who did not give his name in line with department policy, told The Associated Press that the raids were still ongoing.

The Associated Press contributed to this report.