About 1,200 migrants on two different boats were rescued in the Mediterranean on Monday, the Italian Coast Guard said.
One of those boats, a migrant vessel adrift in the Mediterranean with about 400 people on board was in "huge danger" amid high waves on Monday, Sea-Watch International, a nongovernmental rescue operation said.
Italian Coast Guard ships had been dispatched in a rescue operation, the organization said. Another vessel with about 800 people on board also was safely evacuated about 120 miles off the southern coast of Sicily on Monday, according to ANSA, an Italian news agency.
The adrift vessel had departed from Tobruk, Libya, with migrants heading to Europe, according to Alarm Phone, a migrant-aid group.
Around 2,000 people had been rescued by the Italian Coast Guard over the weekend since Friday, the coast guard said. With the combined rescues Monday, the total number of rescues is up to more than 3,000 people since Friday.
"The people on board are in panic and ask for immediate rescue," Alarm Phone said on Twitter.
The vessel had been taking on water on Sunday as it drifted between Greece and Malta in high seas, both organizations said. Sea-Watch said it came across the vessel "in distress" on Sunday after the captain had apparently abandoned ship.
"Two merchant ships that are ordered not to rescue, instead one was asked by Malta to only supply the boat with fuel," Sea-Watch said.
MORE: Migrants in Italy face uncertainty after far-right prime minister's winAlarm Phone said several people had jumped into the water when they saw nearby merchant ships. The ship that had supplied fuel didn't rescue any of the passengers, Sea-Watch said.
"A woman reported the seriousness of the conditions on board. The captain left & there is nobody who can steer the boat," Alarm Phone said. "Several people require medical attention, incl. a child, a pregnant woman & a person with a physical disability."
ABC News' Ellie Kaufman contributed to this report.