SEOUL, May 30 (Reuters) - South Korea's Prime Minister Kim Boo-kyum said on Sunday (May 30) that 1 million doses of Johnson & Johnson's (J&J) coronavirus vaccines will arrive this week, including for 550,000 soldiers, after the United States almost doubled its earlier pledge.

US President Joe Biden, at his first summit with President Moon Jae-in earlier this month, promised to supply shots for 550,000 South Korean troops. The two agreed to forge a vaccine partnership to boost regional and global supplies.

Kim said the shipment of the J&J vaccines had doubled since the summit and will arrive this week, thanking the Biden administration for showing its commitment to the bilateral alliance.

"We plan to administer the vaccines on military-related personnel, including reserve forces and the civil defence corps, after airlifting them directly from the United States using military planes," Kim told an intra-agency meeting.

Around 10 million Americans, including soldiers, have received J&J shots and the incoming doses will be immediately usable upon arrival, he said.

The US Forces Korea had offered to give 13,000 doses of the vaccine ahead of the summit.

Global shortages and shipment delays have posed uncertainties in South Korea's vaccine rollout, deepening public scepticism over its goal of reaching herd immunity by November.

South Korea's food and drug safety ministry granted final approval for the J&J product in April, after signing a deal to import the vaccine for 6 million people, though the date for their shipment has not been finalised.

As of Saturday, around 5.4 million out of the country's 52 million population have received at least a first dose since the inoculation drive began at the end of February, according to the Korea Disease Control and Prevention Agency.

The agency reported 480 new COVID-19 cases, bringing the total to 139,910, with 1,957 deaths.