The number of migrant deaths in the Mediterranean this year reached 3,116, down about 40 per cent on last year's total.
The UN Migration Agency says just over 170,000 migrants and refugees entered Europe by sea in the year to December 20, with the vast majority arriving in Italy.
The arrivals are also down almost 50 per cent compared to last year.
The UN has been working closely with the government in Tripoli to put pressure on people smugglers and the Libyan coast guard has also been given help to intercept boats.
But Human Rights Watch is one of the groups voicing concern about the new strategies regarding Libya, saying more migrants are "being returned to nightmarish conditions in Libya".
In the latest rescues, some 250 migrants were pulled from the sea off the coast of Libya in the early hours of Tuesday morning.
Reports in the Italian media say smugglers have lowered the price of a crossing, partly due to bad weather.
The UN says among those migrants or refugees who drowned this year, 2,832 were headed for Italy, 223 were headed for Spain and 61 were trying to reach Greece.
Globally, 5,362 migrant deaths were reported in 2017.
In 2016, the recorded number of migrant deaths in the Mediterranean stood at 4,967, with 359,160 arrivals to Europe.
Also, the UN began bringing African refugees to Italy from Libya last week, releasing them from detention centres condemned by human rights groups as inhumane.
It is the first time that the UNHCR in Libya has evacuated refugees directly to Europe.
"We really hope other countries will follow the same path," said Vincent Cochetel, the UNHCR's Special Envoy for the Central Mediterranean.
It is reported that as many as 10,000 people being held in detention centres for immigrants in Libya will be evacuated next year.
Italy's Catholic Church will house many of the new arrivals in shelters across the country, as the migrants from Eritrea, Ethiopia, Somalia and Yemen go through the country's asylum request process.
The Reuters news agency says Italy's move to open a safe corridor for some of the migrants deemed as vulnerable "follows criticism by rights groups who have condemned the country's efforts to block migrants in Libya in exchange for aid, training and equipment to fight smuggling".