Two humanitarian groups that have been flying missions over the central Mediterranean in search of smugglers' boats packed with migrants in need of rescue and to monitor possible human rights violations are protesting a move by Italy's civil aviation authority to ground their planes.

The authority, ENAC, confirmed the groundings of the Moonbird, a Cirrus SR22 single-engine aircraft operated by the German group Sea-Watch, and Colibri, a MCR-4S aircraft operated by French group Pilotes Volontaires, saying the light aircraft are approved for recreational and not professional use.

Both groups dispute the decision.

Sea-Watch spokesman Ruben Neugebauer called the grounding political, saying that the Moonbird is in compliance with Italian and national norms.

Neugebauer said it is important to have the planes in the air because they document human rights violations by ships that do not respond to rescue calls or by EU-deployed aircraft that signal the presence of migrant boats to Libyan authorities so they are brought back to Libya. Both the EU and the United Nations have said Libya is not a safe port for migrants, many of whom are subject to detention and torture.

"They know that this is a breach of international law. One reason our missions are so important, and the reason the European Union tries to stop us by any means necessary, is that it is annoying for them that there are eyes at sea that bring up their human rights violations, that are coming up again and again," Neugebauer said.

Jose Benavente Fuentes, a pilot who has been flying out of Lampedusa for Pilotes Volontaires , said two lawyers were working to try to negotiate with Italy's civil aviation authority.

"We do not understand the reason we have been stopped from flying," Fuentes said.

Moonbird previously was blocked from Maltese airspace last year.

ENAC said in a statement that it had been informed by Malta of lapses, which it verified.

It said the Colibri lacked certification to conduct operations beyond recreational activity, "much less on the high seas," and that it had undergone significant modifications that are not traceable. "Search and rescue operations are professional operations that require a system of authorizations that are not compatible with aircraft of an amateur construction," ENAC said.

It said Moonbird was of a similar construction.

Also on Tuesday, Italy's hard-line interior minister, Matteo Salvini, banned a German humanitarian ship carrying migrants rescued off Libya from entering Italian territorial waters.

Decrees such as the one signed Tuesday have become routine in Salvini's bid to prevent humanitarian rescue ships from bringing migrants to Italy.

This one targets a vessel operated by the German group Lifeline that on Monday picked up about 100 people in a rubber lifeboat some 50 kilometers (30 miles) off the Libyan coast. Lifeline has urged the German government to help identify a safe harbor.

While Italy and Malta are the closest European ports, both countries have banned humanitarian rescue ships from their ports. The positions have led to numerous standoffs.

Malta on Monday said its armed forces rescued 162 migrants in its search-and-rescue area in two operations.