Fighting has erupted between Shiite rebels and forces loyal to Yemen's internationally recognized government near the strategic Red Sea port of Hodeida, leaving at least 12 people dead and 25 others wounded from both sides, officials said on Sunday, just two days ahead of the implementation of a cease-fire agreed in talks in Sweden earlier this week.

They said the fighting south and east of Hodeida began Saturday night and continued until Sunday afternoon, a development that does not bode well for a cease-fire in Hodeida, whose port sees about 70 percent of Yemen's food aid and other imports coming into the country.

The cease-fire is expected to go into effect Tuesday, according to the Yemeni officials, who spoke on condition of anonymity because they were not authorized to brief the media.

Yemen's civil war, in which a Saudi-led coalition is fighting against the rebels, has pushed much of the country to the brink of famine. It has already left 22 of its 29 million people in need of aid, according to the U.N.

A cessation of hostilities at Hodeida would spare Yemen a significant spike in civilian casualties since the rebels holding the city have shown battlefield resilience in the face of much larger government-allied forces and airstrikes and will likely not surrender the city without ruinous street-to-street fighting in densely populated neighborhoods.

Speaking Sunday at Doha, U.N. Secretary-General Antonio Guterres warned that if Yemen's humanitarian situation does not improve, 14 million people there will be in need of food aid in 2019, six million more than this year.

"There is a high level of hunger in Yemen," he said. "The fact that famine was not yet declared does not in any way diminish our huge concern with the very high level of hunger that exists in Yemen with a number of people dying in very dramatic circumstances."

Last week, an international group tracking Yemen's civil war reported that the conflict has killed more than 60,000 people, both combatants and civilians, since 2016.

The figure, which did not provide a breakdown of those killed, is much higher than the U.N. figure of 10,000 civilian deaths, and has added to the urgency to find a political resolution for the four-year bloodletting.

The new death toll figure of 60,000 for Yemen came from the U.S.-based Armed Conflict Location & Event Data Project, or ACLED, which said in a report on Tuesday that more than 28,000 people — both civilians and combatants — were killed in the first 11 months of 2018, an increase of 68 percent from 2017. More than 3,000 were killed in November, the deadliest month since ACLED started collecting data.

The group said 37 percent of the total number of civilians killed in Yemen in 2018 died in Hodeida.

ACLED's figures do not include the last few months of 2014, when Yemen's rebels, also known as the Houthis, captured the Yemeni capital Sanaa and much of the country's north, nor the casualties in 2015, when the Saudi-led coalition joined the war on the side of the government.

ACLED bases its figures on press reports of each incident of violence in the war.