The United States has given six patrol boats to the Vietnamese Coast Guard, the US embassy in Hanoi said, amid warming ties between the former foes.

The vessels are in addition to another six patrol boats and a high-endurance cutter provided to Vietnam by the United States last year.

The move is the latest in increased security ties between Vietnam and the United States and follows a landmark visit by a US aircraft carrier to the country in early March.

“The bilateral partnership between the United States and Vietnam continues to reach new heights,” the embassy said in a statement.

Vietnam is the country most openly at odds with China over parts of the disputed South China Sea.

China claims 90 percent of the potentially energy-rich maritime territory, but Brunei, Malaysia, the Philippines, Taiwan and Vietnam also lay claim to parts of it, through which about $US5 trillion of trade passes each year.

Dozens of Chinese naval vessels exercised this week with an aircraft carrier in a large show of force in the area, satellite images obtained by Reuters showed.

The US embassy statement said the patrol boat transfer “demonstrates US support for a strong, prosperous, and independent Vietnam that contributes to international security and the rule of law.”

More boats are due to be delivered and the United States has also provided a training centre, maintenance facility, boat lift, vehicles and a navigation simulator.

The Metal Shark “45 Defiant” patrol boat is manufactured in the United States by Gravois Aluminium Boats LLC.

It can reach speeds of up to 93 km per hour and is suited for both inland and offshore use, according to the manufacturer’s website.

The first batch of boats was delivered to the US Department of Defence to provide “advanced technology to stabilise US interests in South Asia,” the website says.

Reuters