A Chinese people-smuggling gang has been uncovered by French and Spanish police.

The Spanish interior ministry said on Saturday that 75 people have been arrested, 51 in Spain and 24 in France, including the two Barcelona-based suspected heads of the organisation in Europe. Some of the people trafficked ended up in the sex trade, the ministry said.

The gang charged up to £43,000 to transport Chinese nationals to Britain, the US, Spain, France, Greece, Italy and Turkey.

The gang's main European hub was Barcelona airport which was used as a stopping-off point for the trafficked people while false documents were prepared.Six migrants have drowned off Sicily after their vessel ran aground close to shore, according to the Italian coastguard.

Elsewhere, an 18-metre-long fishing boat carrying about 120 migrants ran aground at dawn on Saturday 40 metres from a beach near the city of Catania.

While most of the passengers reached the shore, the six who drowned were apparently unable to swim.

The 120 migrants were mainly from Syria and Egypt, an Italian coastguard, Roberto D'Arrigo, told Sky Italia television.

African migrants normally reach Sicily's more southern coast or the island of Lampedusa to the south, only 110km (70 miles) from Tunisia in North Africa. D'Arrigo said a migrant boat had never previously put in to Catania – halfway up Sicily's eastern coast – leading him to believe the boat had lost its way.

Thousands of immigrants seek the southern shores of Italy every summer, when Mediterranean waters in the Strait of Sicily calm sufficiently for small boats to make the crossing from Libya or Tunisia.

They come looking for work in the EU and many do not remain in Italy. Those who do, or who are taken into Italian custody, can be sent home.

Another boat carrying about 90 migrants arrived safely on Sicily's south-east shore on Saturday, near the town of Syracuse.

Last month Pope Francis, in his first official trip outside Rome, celebrated mass on Lampedusa to commemorate the thousands of migrants who have died at sea.

According to the United Nations refugee agency, UNHCR, almost 8,000 migrants and asylum seekers landed on the coasts of southern Italy in the first half of the year. The vast majority were from north Africa, mainly Libya, which has been in turmoil since the overthrow of Muammar Gaddafi in 2011.

The UNHCR said 40 people were known to have died crossing from Tunisia to Italy in the first half of the year, though it is thought that many deaths are never reported.

Last month the Italian coastguard co-ordinated the rescue of 22 migrants after their boat sank off the coast of Libya. But 31 others were feared drowned in the incident, including a baby and four pregnant women, according to the UNHCR.