An Italian helicopter crew scrambled to save hundreds of migrants apparently abandoned on a cargo ship on Friday in rough seas by smugglers in the Mediterranean.

The Italian air force said it sent a helicopter from an air base in southern Italy to help the Ezadeen, a Sierra-Leone-flagged vessel, so sailors could be lowered to secure the ship and doctors allowed on aboard.

Coastguard commander Filippo Marini said early on Friday that a migrant had been able to operate the ship’s radio and called for help saying: “We’re without crew, we’re heading toward the Italian coast and we have no one to steer.”

Exactly how many were aboard was unclear, but the ANSA news agency said there could be as many as 450. The Ezadeen was some 40 miles (64 kilometres) off Italy’s southeastern tip.

“Because of the difficult weather conditions the ship can only be boarded from the air,” the air force said in a statement.

The coastguard asked for assistance from Icelandic patrol boat Tyr, which was in the area on a mission with Frontex, the European Union’s border agency.

The Tyr was able to draw alongside the runaway ship, but the weather conditions made boarding impossible.

The Icelandic vessel has three doctors on board who will be winched on to the merchant ship by helicopter to treat any unwell passengers, the air force said.

The incident comes two days after Italian sailors intercepted a freighter carrying more than 700 mostly Syrian migrants which had been heading for the rocks of Italy’s southeastern shore on autopilot, having been abandoned by the people smugglers who had navigated it from Turkey via Greek waters.

In that incident, the Moldovan-registered Blue Sky M cargo ship got to within five miles – 45 minutes’ sailing time – of a disaster before six navy officers were lowered on to the ship by helicopter and succeeded in bringing it under control.

The vessel’s human cargo included some 60 children and two pregnant women, one of whom gave birth on board as the boat headed towards the coast, according to the Italian Red Cross.

Many of the migrants on the ship were treated for hypothermia and broken limbs.

Italy has also had to grapple with the aftermath of the Norman Atlantic ferry disaster in which at least 13 people have died following an onboard fire that erupted before dawn on Sunday in waters off Albania.

The number of people attempting to reach Europe by sea from the Middle East, Africa and Asia reached a record in 2014.

More than 170,000 people have been rescued by Italy in the last 14 months and hundreds, possibly thousands, have perished trying to make the crossing.

They are almost invariably under the control of traffickers who earn thousands of dollars for every person they put to sea from Libya and other departure points in North Africa.

Increasingly, the traffickers appear to have decided that the best way to get the people to Europe is to put to sea and then abandon the boats.

Since the onset of winter they have been using bigger boats than the converted fishing boats and dinghies they previously favoured.