Libyan naval forces have denied accusations by a rescue organization that one of their crew had attacked a migrant boat packed with around 150 people, causing many to fall into the sea and at least four to drown.
A spokesman for the naval forces in Tripoli, Ayoub Qassem said a patrol had only boarded one vessel to check why it was in Libyan waters.
Germany-based Sea-Watch, one of several non-governmental organizations operating vessels off the coast of Libya, said on Friday a speedboat marked "Libyan Coast Guard" swooped in as they went to the aid of an overcrowded rubber boat in the early hours.
At least one man from the Libyan vessel jumped into the rubber boat and beat the migrants with a stick, causing a mass panic a Sea-Watch spokesman said. Part of the rubber boat deflated in the ruckus, toppling most of them into the sea. No firearms were used.
The Sea-Watch crew said it recovered four bodies, but saw others in the water it was not able to retrieve. Of an estimated 150 people on board the rubber boat, Sea-Watch rescued 120.
But Qassem said this was not correct.
"The crew alleged that we attacked them and a number of casualties have been reported but this is not true at all, and we call on them to prove this incident if they are right," he said.
Qassem said that at around 2:30 am on Friday, the coast guard of the western region of Libya spotted three vessels off the coast. The patrol commander boarded the vessel and found Sea-Watch was involved.
"The commander asked them why they are in the Libyan waters, but the crew of the organization did not answer logically. The crew was asked to leave," he said. "It's a breach and disrespect to Libyan sovereignty according to international rules and norms."
Sea-Watch spokesman Ruben Neugebauer said from Berlin that the position of their ship, the Sea-Watch 2, was about 14 nautical miles off the coast of Zuwarah, Libya, while territorial waters end at 12 nautical miles from the coast.
"It was definitely not in Libya waters," Neugebauer said of the position of the Sea-Watch 2, offering Reuters historical GPS tracking data from the ship.
"We should have some images at least from the cameras on board," Neugebauer said. "Because it was dark, we don't know how much they have seen, but we hope we have something."
The Libyan coast guard boat sped away when the migrants fell into the sea instead of going to their aid, Neugebauer said.
"This was an attack on our rescue operation. We were engaged already with the boat to hand out life jackets, which is very important because the situation is very dangerous," he said.
Migrant rescues are often complicated in Libya, where the U.N.-backed Tripoli government struggles to impose its authority. The Libyan coast guard is under-equipped and police units are run by some of the competing armed brigades.
Western governments are backing the Tripoli government hoping it can unite rival factions and help better coordinate efforts to combat Islamist militants and migrant smugglers who both profited from Libya's chaos
But brigades of former rebels who fought together against Muammar Gaddafi in 2011 remain powerbrokers. Their rivalries and loyalties to their regions have in the past complicated Western efforts to train up a national army and law enforcement agencies.
The incident happened before the planned start of training next week of up to 100 Libyan coast guard members as part of the E.U. anti-smuggling mission Operation Sophia.
In August, another humanitarian group that operates rescue ships off the coast of Libya, Doctors Without Borders, said it had been attacked and boarded by armed men on a Libyan navy boat. The Libyan navy said it fired "warning shots" because it thought the ship was involved in people smuggling.