An Italian judge ordered yesterday the release of a Spanish non-governmental organization's (NGO) migrant rescue boat, which was impounded by prosecutors last month. The legal case is part of a wider political and legal clash between humanitarian NGOs and Italian authorities who wish to regulate and restrict the flow of migrants into the country.

The decision by Ragusa pre-trial judge Giovanni Giampiccolo was reported by Italian news agency ANSA and confirmed by a spokeswoman for the Spanish charity, Proactiva Open Arms.

"It is only a first step, and good news," the charity's founder Oscar Camps tweeted. He said that his organization remained under criminal investigation.

"We won a battle but I think that the legal war does not end today, it will continue and it will be long," Alessandro Gamberini, a lawyer for Proactiva Open Arms, was quoted as saying by ANSA.

Gamberini is defending Open Arms mission chief Ana Isabel Montes Mier, one of the two members of the Spanish NGO who are being investigated for abetting illegal migration.

As part of the same investigation, the Open Arms vessel was impounded on March 18, a day after it docked in Pozzallo, Sicily, with 216 rescued migrants it refused to hand over to the Libyan coastguard.

Catania Prosecutor Carmelo Zuccaro started a legal case against Proactiva because the NGO dodged Libyan orders and then took the migrants to Italy, rather than to the closer port of Malta.

The Spanish NGO insists it cannot allow people to be returned to Libya, where they risk torture and abuse. It also said the Libyans threatened to shoot at its personnel.

Zuccaro's office initially announced investigations against three Proactiva officials, but managed to identify only two. Three weeks ago, it was stripped of responsibility over the affair.

On March 27, another pre-trial judge dropped the more serious crime of criminal association against the two remaining Proactiva suspects, and moved the case from Catania to Ragusa, another Sicilian town.

German migrant rescue NGO Jugend Rettet is facing a similar legal ordeal. Its ship was impounded in August by other Sicilian prosecutors who suspected the group of abetting illegal migration. The charity is fighting to have the boat back, and Italy's top appeals body, the Court of Cassation, is due to rule on the case on April 23. "These are two different cases but [the decision of the Ragusa judge] makes us hopeful," Jugend Rettet spokesman Philipp Kuelker told dpa, stressing that no member of the NGO has so far been charged.