"Over 150 migrants are being returned to Libya by the coast guard", the agency tweeted.
The migration agency said its team in Libya stood ready to assist the migrants but stressed that the North African country was not a safe port due to intensifying clashes on the ground.
The watchdog argues that migrants in Libya face arbitrary detention, abuse, and human rights violations.
The Mediterranean remained the main gateway to Europe for migrants from Africa, Central Asia, and the Middle East last year, with over 110,000 making it to the shore. More than 1,200 drowned.