Feb 23 (Reuters) - At least three U.S.-bound cargo ships are preparing to load with soybeans at two ports in Northern Brazil in the first such bulk shipments since last summer, according to shipping lineup data seen by Reuters.

The unusual shipments from Brazil, the top global soy supplier, to the United States, the No. 2 exporter, are expected to arrive by early spring, several weeks earlier than past Brazil-to-U.S. shipments as current prices for importing beans from the South American nation are considerably lower, analysts said.

Although U.S. farmers harvested a sizable crop last autumn, Brazilian farmers gathered a record crop last year and are currently harvesting what is projected to be their second-largest crop on record.

"As Brazil has very low prices, we have a difference of around $50 per ton between FOB (free on board) port prices here and there in the USA. This more than covers the logistical cost of getting Brazilian soy into the U.S.," said Daniele Siqueira, analyst with AgRural.

Brazilian soy exports to the United States soared to around 420,000 tons in 2023, up from only about 4,000 tons the previous year, according to Brazil's Agriculture Ministry.

Shipments scheduled for 2024 already total more than 100,000 tons, according to maritime agencies.

The vessel Yasa Mimosa is at anchor near Santarem port and the vessel UBC Tilbury is anchored near Itacoatiara port, each waiting to load with around 35,000 metric tons of soybeans bound for the United States, according to data from shipping agency Cargonave.

A third vessel, the Kian, is scheduled to arrive at Itacoatiara next week for loading with around 34,000 tons of soybeans, shipping lineup showed.

The charterer of all three vessels was livestock and poultry producer Perdue Farms, which operates a port terminal and crushing facilities on the U.S. East Coast.

A Perdue Farms spokesman declined to comment on the shipments.

Benchmark Chicago Board of Trade soybean futures posted their 10th straight weekly decline and fell on Friday to the lowest point in more than three years on the news. (Reporting by Karl Plume and P.J. Huffstutter in Chicago and Roberto Samora in Sao Paulo; Editing by Andrea Ricci, Will Dunham and Ros Russell)