Los Angeles,  A US Navy hospital ship has docked at the Port of Los Angeles to aid California's COVID-19 response as the number of new confirmed cases continued to surge.

The ship, Mercy, carrying more than 800 Navy medical personnel and support staff, will provide 1,000 hospital beds as a "referral hospital" to treat non-COVID-19 patients, reports Xinhua news agency.

It will also help relieve the strain being put on local hospitals by the COVID-19 pandemic.

The Mercy, which docked on Friday morning, also has 11 general-purpose operating suites, a 5,000-unit blood bank, 15 patient wards and room for 80 intensive care beds, according to the ship's official website.

It can produce at least 7,000 meals and 200,000 gallons of freshwater daily.

Mercy, homeported in San Diego, is one of the two hospital ships operated by the US Navy.

The ship was initially bound for Seattle, Washington, which is also one of the states hit the hardest by COVID-19 pandemic.

The plan for Seattle was changed as officials projected more needs for beds in California.

President Donald Trump approved California Governor Gavin Newsom's request on Sunday to deploy the ship to Los Angeles to provide additional medical support.

Newsom's office posted a video which shows the huge white-hulled hospital ship docking at the Port of Los Angeles on Twitter, noting that the ship will increase California's hospital capacity during the COVID-19 outbreak.

"Glad to welcome the @USNavy's USNS Mercy to Los Angeles. This ship brings 1,000 new medical beds to the @PortofLA, helping ease the burden on our emergency rooms and ICUs when the cases of COVID-19 grow in the weeks ahead," Los Angeles Mayor Eric Garcetti, tweeted on Friday morning.

"Thank you to all our partners for making this possible," he added.

There are more than 4,200 positive cases and 85 deaths related to COVID-19 in California so far, according to a real-time Los Angeles Times survey.

The COVID-19 death toll in Los Angeles County nearly doubled on Thursday, reaching a total of 21, while another 421 cases were confirmed for a total of 1,216 as of Thursday night, according to the Los Angeles County Department of Public Health.

The overall number of confirmed COVID-19 cases in the US now stands at 104,686, with 1,707 deaths, according to the latest update by the Washington-based John Hopkins University.