Mexican President Andres Manuel Lopez Obrador said on Friday the United States would probably send Mexico around 5 million more doses of the AstraZeneca COVID-19 vaccine, saying a factory set to make the drug domestically was not yet ready.

Struggling with delays at the factory and shortfalls in deliveries from foreign vaccine suppliers, Mexico has asked the United States for more shots after an initial loan of some 2.7 million AstraZeneca doses.

“It’s probable that they help us with a loan, while the AstraZeneca plant in Mexico gets up and running,” Lopez Obrador said at a regular news conference.

The US State Department did not immediately respond to a request for comment.

Under a deal reached last year, the mAbxience laboratory in Argentina manufactures the active ingredient of the vaccine and then ships it for bottling to a factory in Mexico owned by a company called Liomont.

Argentina has delivered cargos of the active ingredient to Mexico but a series of regulatory approvals and reviews have delayed Liomont’s commercial production from an original target of March.

The doses bottled in Mexico are intended to be distributed across Latin America and the delays have affected vaccination programmes  in the region. Argentina’s government this week formally requested a report on production from AstraZeneca.

AstraZeneca and Liomont did not immediately respond to requests for comment.

In Mexico, the problems have been compounded by deliveries of far fewer Sputnik V doses from Russia than had been agreed, and lower volumes than expected of Pfizer coronavirus vaccines.

The United States has already provided some AstraZeneca vaccines to Mexico, sending around 2.7 million doses in two shipments between late March and the start of April.

Reuters reported on Thursday that Pfizer Inc will ship doses made in its US plant to Mexico for the first time.