Rescuers saved some 1,400 migrants off the coast of Libya on Monday as Italy announced a record number of people arriving this year after crossing the Mediterranean, authorities said.

"It was a very difficult day but thanks to the work of the units that helped out, all of the migrants were rescued," a spokesman for the Italian coast guard, which coordinates the operations, told AFP.

The unseaworthy condition of the migrant boats and the sheer number of people packed onto them make the journey dangerous even in summer, but colder months add increased risk of hypothermia and rough seas.

Italian, Irish and charity group ships, along with commercial vessels, helped rescue the migrants from 11 inflatable dinghies and two small boats.

Authorities in Italy said Monday they had recorded a record number of arrivals by sea this year, with one month still to go in 2016.

Over 171,000 migrants have arrived, which beats the previous annual record of 170,100 from 2014. The tally does not include Monday's rescues.

The vast majority of the migrants landing in Italy come from Africa and begin their sea crossings from Libya, typically paying traffickers several hundred dollars for the journey.

With Italy's neighbours having tightened their borders, the numbers being housed in reception facilities across the country have risen to an unprecedented total of over 176,000, prompting howls of protest from some local authorities.

Many migrants arrive in Italy with the intention of travelling north, often to try and rejoin relatives, with Germany and Sweden among the popular destinations.

At least 4,690 migrants are confirmed to have died or disappeared in the Mediterranean so far this year, according to counts by the International Organization for Migration and the UN refugee agency.