HANOI (Reuters) - The U.S. Coast Guard transferred a high-endurance cutter to its Vietnamese counterpart in Honolulu, the U.S. Embassy in Hanoi said on Friday, in the latest effort to deepen ties with its former foe.

The move follows an increase in exchanges between the two countries, ahead of a visit to the United States next week by the Vietnamese prime minister and a recent delivery of six patrol boats to the Vietnamese coast guard.

The ship will help the Vietnam Coast Guard carry out maritime law enforcement, and conduct search and rescue and other humanitarian response operations, the embassy said in a statement.

“This cutter provides a concrete and significant symbol of the U.S-Vietnam comprehensive partnership,” said U.S. Coast Guard Rear Adm. Michael J. Haycock, its chief acquisition officer.

The transfer is part of the U.S. Excess Defense Articles program that offers excess military equipment to U.S. partners and allies in support of modernisation efforts, the embassy said.

Vietnam is the country most openly at odds with China over the busy waterway in the disputed South China Sea since the Philippines President Rodrigo Duterte took a softer line with Beijing and is cultivating its ties among major powers.

China claims 90 percent of the potentially energy-rich South China Sea. Brunei, Malaysia, the Philippines, Taiwan and Vietnam lay claim to parts of the sea, through which about $5 trillion of trade passes each year.

The coast guard exchanges between the United States and Vietnam follow the first visit by a Chinese coast guard vessel to the southeast Asian nation last November and a visit by a Vietnamese coast guard vessel to China early in May, its first ever foreign visit.