HANOI, July 25 (Reuters) - Vietnam may get more COVID-19 vaccine donations from the United States as it struggles to control outbreaks of the fast-spreading Delta variant, the country's ambassador to the United States said on Sunday.

Vietnam took delivery of a shipment of 3 million Moderna doses from the United States on Sunday, which brought the amount given by the United States, via the global COVAX vaccine scheme, to 5 million doses.

"The U.S. side has said it is also considering more vaccine donations to Vietnam soon," the ambassador to the United States, Ha Kim Ngoc, said in a speech posted on a government website.

Vietnam successfully contained the virus for much of the pandemic, but has faced recent rapid outbreaks of infections, with daily cases repeatedly hitting new highs.

Vietnam is also in talks with the United States on domestic production of mRNA vaccines, its foreign ministry said on Thursday, adding that production could begin in the fourth quarter or early in 2022.

Health Minister Health Nguyen Thanh Long said on Sunday that construction of a plant producing vaccines under U.S. technology was underway, adding that production would start in the first half of 2022. It was not clear if he was referring to the same plan mentioned by the foreign ministry.

The foreign ministry and Long did not identify the U.S. and Vietnamese companies involved in the plans.

State media reported on Saturday Vietnamese conglomerate Vingroup was in talks with San Diego-headquartered Arcturus Therapeutics Holding on mRNA vaccine production.

Clinical trials could begin in Vietnam in August, the Tuoi Tre newspaper reported, adding that the firms could produce 100 million to 200 million doses a year under such a deal.

Vingroup and Arcturus did not immediately respond to requests for comment.

The health ministry reported 7,531 infections on Sunday, just down from Saturday's record daily increase of 7,968.

In all, it has recorded more than 98,000 infections and at least 370 deaths, most in the southern commercial hub of Ho Chi Minh City and its neighbouring provinces. (Additional reporting by James Pearson Editing by Frances Kerry)