A Maersk Tankers vessel has been stuck at anchor off Malta for five days after rescuing migrants who have been blocked from stepping ashore on the Mediterranean island nation.

Migrant rescue organisation Alarm Phone said the 36,900-dwt Maersk Etienne (built 2004) picked up about 27 people, who have been denied permission to disembark by the Rescue Coordination Centre (RCC) of Malta.

"In this way, RCC Malta prevents them from finally reaching land and from enacting their right to seek asylum," Alarm Phone said.

RCC Malta did not immediately respond to TradeWinds' request for comment.

Alarm Phone spokesman Maurice Stierl said Maersk Tankers told the group that Maltese authorities have not assigned the ship a port at which to disembark the migrants.

"We are unclear about the reason but, based on our experience, the Maltese authorities are seeking to prolong the suffering of the migrants and the crew on board in order to create a deterrence effect, also so that future cargo vessels would think twice about rescuing and seeking to disembark in Malta," he said.

Tracking data from VesselsValue shows the ship has been at anchor off Malta since 5 August.

"We are working with relevant authorities to safely disembark the migrants," Maersk Tankers said.

Stierl said that Alarm Phone does not know the well-being of the migrants onboard the Mearsk Etienne, although the group has offered support.

Tunisia-bound

The Danish-flag product tanker was bound for the port of La Skhirra, Tunisia, on 4 August, presumably to load a cargo, when it was called to rescue the migrants, according to vessel tracking data and tweets by the organisation.

The company said the Maersk Etienne received the call from Maltese officials to aid migrants on a small boat and then helped them embark on the tanker.

"The crew has provided them water, food and blankets and will continue to support them in accordance with the International Convention for the Safety of Life at Sea," Maersk Tankers said.

Alarm Phone said that it first received a call from the migrants on 3 August after they left Libya on a small boat. There were 26 men and one woman on the craft.

"They told us that they had engine problems and that water was entering their boat," Stierl said.

The next morning, their vessel broke down and drifted into contested waters off Libya.

Alarm Phone accused RCC Malta and the country's armed forces were "failing to rescue" the 27 people.

And the group said that at first, Maersk Tankers was monitoring the situation without rescuing the migrants, leading to concerns that the Maersk Etienne was waiting for Libyan coastguards to step in. That, Alarm Phone feared, would have forced the migrants back into a war zone.

Maersk Tankers spokeswoman Kis Soegaard, however, said the Maersk Etienne was providing shelter to the migrant boat.

At the time, the non-governmental organisation apparently sought to use Twitter to put pressure on the Danish shipowner, tagging its handle on the social media platform with its posts.

The next day, Alarm Phone said it received confirmation the tanker had rescued the migrants, who had spent more than 34 hours in distress.