At least 64 people drowned in the Mediterranean Sea this weekend after the overcrowded rubber dinghy they were traveling on sank off the coast of Libya.

The group in the dinghy, which migration officials said was aided by smugglers and bound for Italy, became the latest casualties in a continuing crisis. More than 3,000 refugees and migrants died in the Mediterranean last year while trying to make their way to Europe.

The deaths on Saturday focused attention on the dangerous central Mediterranean crossing between Libya and Italy, where most of those deaths took place, and they prompted calls from the United Nations migration agency for a comprehensive policy to address the humanitarian crisis.

“This is the beginning of the year, and this is quite dramatic after only eight days,” said Flavio Di Giacomo, an agency spokesman.

Footage of the rescue operations on Saturday, taken by rescuers from the Italian Coast Guard, shows dozens of people desperately clinging to a partly deflated rubber dinghy.

According to survivor accounts collected by the United Nations agency, smugglers had packed more than 150 people onto a flimsy rubber dinghy on the Libyan coast. The vessel began to take on water after eight or nine hours at sea. People panicked and fell into the water.

When the Italian Coast Guard arrived, it rescued 86 people from the water and retrieved eight bodies. Dozens more remain unaccounted for and are presumed dead.

Mr. Di Giacomo said smugglers must be held accountable for their role in the deaths.

“If you let an unseaworthy dinghy with 150 people sail, that could never handle all of these people,” Mr. Di Giacomo said. “With this sea, in January, it’s not an incident anymore, this is a crime. The smugglers are committing a crime.”

Most of those aboard the vessel were from sub-Saharan Africa and included people from Cameroon, Gambia, Ivory Coast, Mali, Nigeria, Senegal and Sierra Leone.

The survivors were transported to Catania, a port city on the east coast of Sicily, on Monday.

At least five children between 2 to 6 years old drowned. There were also four children, ages 2, 3, 9 and 10, among the survivors, one of whom lost her mother.

The episode was not the only one to take place in the area over the weekend. On Sunday, 270 other migrants were rescued by the Libyan Coast Guard, probably from more than one dinghy, according to Mr. Di Giacomo.

The rescue crew recovered 12 bodies.

“This is not an emergency in terms of numbers, but this is a humanitarian emergency,” Mr. Di Giacomo said.

He said the only way to halt the continuing deaths in the Mediterranean was to organize a comprehensive rescue operation and provide alternative ways for migrants to travel to Europe.

“There are no regular ways to come to Europe,” he said, “so the only ways for migrants to come is to rely on these unscrupulous smugglers and traffickers.”