Some 250 migrants rescued by an Open Arms vessel in international waters between New Years' Eve and January 2 are being taken to a quarantine ship at Porto Empedocle in Sicily, the NGO has reported.

The migrants include a group of 96 who were reportedly picked up from a boat in Malta's search and rescue area on Saturday. 

NGO Alarm Phone, which provides a hotline for migrants in distress at sea, said that the Maltese authorities ignored a request for assistance. Among the group were 17 minors and two women.

Alarm Phone said that Malta's rescue co-ordination centre either didn't pick up the phone or hung up immediately. 

The Open Arms vessel, which picked up the 96, was already carrying 157 migrants from a rescue which took place on December 31 outside the Libyan search zone.

In a tweet late on Sunday, Oscar Camps, the founder of the Open Arms NGO, said Italy had confirmed a safe port in Sicily. 

He shared a video showing the conditions on board deteriorating rapidly due to storming weather. 

"This same situation on a boat would be certain death," he said. "After Malta's refusals to allow us to disembark, Italy has just confirmed a safe port for us: Porto Empedocle, Sicily."