ROME (Reuters) - International humanitarian group Save the Children said on Monday it had suspended migrant rescues in the Mediterranean Sea as departures from Libya slow and security conditions worsen. Save the Children has operated a ship, the Vos Hestia, since September last year, rescuing more than 10,000 migrants from dangerous and overcrowded boats launched by people smugglers.  For too long we have been the substitution for the inexistent and inadequate European policies for search and rescue and for hosting migrants,  Save the Children Director General Valerio Neri said in a statement.   Italian police searched the Vos Hestia on Monday as part of a wider investigation into the role non-government organizations are playing in picking up migrants off the Libya coast and bringing them to Italy. Save the Children said its decision to halt rescues was already planned before the police search. Earlier this year, the government asked humanitarian groups to sign a  code of conduct . The government said the rescuers were providing an incentive for smugglers to put migrants to sea. Police in August seized a migrant rescue boat operated by a German aid group Jugend Rettet. The chief prosecutor in the Sicilian city of Trapani said he had evidence of encounters between traffickers, who escorted illegal immigrants to the NGO boat, and members of its crew. Jugend Rettet denied any wrongdoing. Save the Children said in a statement it was not under investigation and was cooperating with authorities. The documents seized by police on Monday concerned  presumed illegal actions committed by third persons , it said. Several months ago some 10 rescue ships took turns patrolling the North African coast, picking up migrants who reached international waters and bringing them to Italy.  Now only one large ship and a few small ones remain, with many organizations   including Doctors Without Borders   pulling out for various reasons, including security concerns and unhappiness with the attitude of the Italian authorities. The Libyan Coast Guard, funded and trained by Italy, has taken a hostile stance toward the humanitarian boats in a series of incidents on the high seas.  In August, a Libyan vessel intercepted a charity ship and ordered it to sail to Tripoli or risk being fired on. Departures from Libya have fallen dramatically since July, when an armed group that had been deeply involved in smuggling from the city of Sabratha began blocking departures. So far in October sea arrivals to Italy are down more than 75 percent compared with the same month last year. 