ROME (Reuters) - A Spanish aid group operating in the Mediterranean said on Tuesday one of its boats had been barred by Italy and Malta from disembarking migrants rescued two days ago.

Humanitarian groups have played a growing role in rescuing migrants who pay criminal gangs for passage from Libya, prompting accusations in Italy that they are facilitating people smuggling and encouraging migration. The groups deny this.

It was not clear why the Golfo Azzurro, run by Barcelona-based Proactiva Open Arms, was not allowed to dock in Lampedusa. It is now in international waters.

The Italian coastguard could not be reached for comment.

“Golfo Azzurro rescued three people 100 miles from the Libyan coast in an (Italian) coastguard operation 48 hours ago and we are still without authorization to disembark,” Proactiva said on Twitter.

The Italian interior ministry has proposed a code of conduct which Proactiva signed in Rome on Tuesday, although some groups refused to endorse it.

European states have squabbled over how to deal with the flow of more than 600,000 migrants to Italy since 2014. Italy says the European Union has not given enough help and migration looks set to be an issue in national elections due next year.

Malta said it could not allow the migrants on board the Golfo Azzuro to disembark because they should be taken to Lampedusa, the nearest port to where the rescue took place.

“Malta’s decision is in line with international law,” Malta’s Deputy Prime Minister Chris Fearne told reporters.

REPORTED THREAT

Most Mediterranean boat migrants are sub-Saharan Africans and Bangladeshis who are rescued from rubber dinghies 12 miles north of Libya, but Proactiva said the three rescued on Sunday were Libyan.

Golfo Azzurro mission chief Albert Mayordomo said in a video they were instructed by Italy’s coastguard to look for the boat, which they found after 17 hours.

Proactiva said a second boat it operates received a threatening radio call from the Libyan coastguard on Monday morning while patrolling international waters some 13 miles from the Libyan coast between Tripoli and Zuwara.

In an audio recording sent to Reuters, a man’s voice can be heard saying: “There is information that you are dealing with smugglers. Do not come back close to our waters. Next time you will be targeted.”

The spokeswoman said the Libyan coastguard had fired shots into the air in the direction of the NGO boat.

A Libyan coastguard spokesman said one of its patrol vessels had fired two shots into the air after finding the Spanish boat exactly 12 miles from the Libyan coast, an area he said was for Libya to patrol.

“We demanded they leave immediately and head north but they did not obey the instructions,” coastguard spokesman Ayoub Qassem said.

It seemed they were waiting for an illegal migrant boat, he said.

“Our patrol vessel had to warn them and we fired twice in the air ...(the NGO boat) vanished and left for the north with empty hands.”

The European Union is providing training and funding for the coastguard in Libya, which became the most common departure point for people trying to reach Europe by sea in the turmoil following the 2011 overthrow of Muammar Gaddafi.