A total of 575 migrants have been intercepted off Libya's western coast in just a week, the UN's migration agency said Tuesday.
"In the period of 27 October to 2 November, 443 migrants were rescued/intercepted at sea and returned to Libya," the International Organization for Migration (IOM) said in a tweet.
On Tuesday morning, a further 132 migrants were intercepted at sea and taken to Tripoli's naval base, it added, without giving details on their nationalities.
Human traffickers have taken advantage of persistent violence in Libya since the 2011 fall of dictator Moamer Kadhafi, turning the country into a key corridor for migrants fleeing war and poverty in desperate bids to reach Europe.
While many have drowned at sea, thousands have been intercepted by the Libyan coast guard, which has been backed by Italy and the EU, and returned to Libya.
They mostly end up in detention, often in horrific conditions.
Rights group Amnesty International has denounced the policy and called on the EU to review its cooperation with Libya.
The IOM has also campaigned to end returns to the North African country, 300 kilometres (185 miles) from the Italian coast.
Since January, Libya's coast guard has intercepted around 10,000 people at sea, while 500 others have died in the central Mediterranean, according to IOM figures.
The agency warns the real number of fatalities may be much higher.