The world’s top smartphone maker announced earlier this month a recall of at least 2.5 million Note 7s across the globe due to faulty batteries causing some of the phones to catch fire. The firm is already issuing replacement devices using what it says are safe batteries in several markets including South Korea and the United States.

The Korean Agency for Technology and Standards, in a statement, formally approved the recall plan and said the new batteries being used are safe.

The agency ordered Samsung to have its supplier conduct x-ray tests on the batteries prior to shipment. It also ordered Samsung to carry out inspections on its own as an additional safeguard and to extend the refund deadline to Sept. 30 from Sept. 19 previously.

Read: Another Galaxy Note 7 explodes in hotel room, causes damage: reports

Samsung declined to comment on how many phones are being recalled in South Korea, but the firm’s report to the agency dated Sept. 2 seen by Reuters showed that 429,000 Note 7 phones had been sold prior to the recall. The firm said it is in talks with domestic carriers to offer a 30,000 won ($27.21) mobile tariff credit to affected customers for their October bill.

The South Korean firm is pushing to get its recall completed as quickly as possible in order to limit damage to its reputation and earnings, and resume sales. Some analysts said the recall could cost Samsung nearly $5 billion in lost revenue.

Samsung, which halted Note 7 sales in countries affected by the recall, plans to resume new sales of the Note 7 in South Korea on Sept. 28.