Pfizer Inc. said on Thursday it was not facing any production issues with its COVID-19 vaccine, a day after U.S. officials pointed to challenges with the company's manufacturing.

The company said it was confident in its ability to deliver up to 50 million doses globally this year and up to 1.3 billion next year.

"No shipments containing the vaccine are on hold or delayed. This week, we successfully shipped all 2.9 million doses that we were asked to ship by the U.S. Government to the locations specified by them," Pfizer said in a statement.

The U.S. government has signed a deal with Pfizer for a 100 million doses of the vaccine, which has started being rolled out across the country under an emergency use authorization.

Pfizer had reported some production issues with the vaccine, U.S. Secretary of Health and Human Services Alex Azar said on Wednesday. He had said the U.S. government would provide the company full support to ensure it can produce the vaccine for American people.

Reporting by Manas Mishra in Bengaluru; Editing by Anil D'Silva