April 14 (Reuters) - The U.S. Food and Drug Administration has asked Eli Lilly for more data on liver injury linked to its newly approved obesity pill, ⁠according to a letter posted on the health regulator's website.

The weight-loss pill, branded Foundayo, a once-daily oral medication that targets the GLP-1 hormone, won approval earlier ⁠this month under the Commissioner's National Priority voucher program, which aims to speed FDA decisions on drugs deemed critical to public health ⁠or national security.

A Lilly spokesperson said to ‌Reuters that there have been no indications of liver damage associated with the drug in late-stage testing.

"The FDA approved Foundayo based on its review of data from the ATTAIN clinical program, with post‑approval requirements consistent with the agency's standard approach to ongoing safety evaluation of newly approved medicines," the spokesperson added.

The FDA letter, which was signed on April 1, also ‌said Lilly must conduct post-marketing trials to assess risks related to cardiovascular events and delayed gastric ​emptying.

The drugmaker ‌is required to also conduct a milk-only lactation study ‌in lactating women who have received a dose of the pill to assess concentrations of the drug in breast milk using a validated assay.

The ⁠Department of Health and Human Services, which oversees the FDA, did ‌not immediately respond to Reuters requests ⁠for comments.

Lilly is already conducting a trial ​comparing the pill with insulin glargine in participants with ‌type 2 diabetes and obesity who are at increased cardiovascular risk.

The FDA also asked Lilly to run a trial using ultrasound to measure the effects of temporary treatment interruption and fasting duration on retained gastric contents, to evaluate ​delayed gastric emptying associated with the drug.

"While the inclusion of several post marketing ‌studies ‌following Foundayo's approval is notable, we do not expect these studies to have any meaningful impact on the competitive positioning ‌of Lilly's asset," said BMO ​Capital Markets analyst Evan Seigerman.

"We view this as a reflection of conservatism from (the) FDA."

Lilly began selling Foundayo last week, heating up the battle with Danish rival Novo Nordisk's Wegovy pill, which has been on the ⁠market since January.

In trials, Foundayo led to an 11% reduction in body weight over 72 ‌weeks and oral Wegovy led to about a 14% reduction over 64 weeks.

(Reporting by Sriparna Roy, Christy Santhosh ​in Bengaluru; Editing by Tasim Zahid and Shinjini Ganguli)