March 19 (Reuters) - Potential buyers of Japan's Seven & i ( SVNDF ) and Canada's Alimentation Couche-Tard's ( ANCTF ) U.S. stores have until the end of March to express interest and address antitrust concerns, Bloomberg News reported on Wednesday.

Some potential buyers are engaged in the process, and have signed non-disclosure agreements, Bloomberg reported, citing people familiar with the matter. It did not name any of the interested parties.

Couche-Tard, which operates the Circle-K convenience stores in Canada and the United States, has been trying to acquire Seven & i ( SVNDF ) since August.

The Canadian company said last week it was prepared to bolster its most recent buyout offer of $47 billion if the 7-Eleven convenience store owner became more cooperative and revealed more financial information.

However, the deal has been embroiled in antitrust concerns, with Seven & i ( SVNDF ) opposing the bid, citing U.S. competition law as a barrier to any transaction.

The companies are the top two players in the U.S. convenience store market, with about 20,000 locations between them. Seven & i ( SVNDF ) said last week that more than 2,000 stores could be divested, but Couche-Tard has not provided a figure.

Couche-Tard did not immediately respond to Reuters' requests for comment.

A Seven & i ( SVNDF ) spokesperson said the company had signed non-disclosure agreements with potential buyers and continued to engage with Couche-Tard on antitrust issues.

Any initial expression of interest would need to protect competition in the U.S. market, the Bloomberg report said.

Seven & i ( SVNDF ), which has been the target of investor criticism over its capital allocation for years, said this month that talks had kicked off with Couche-Tard over a store sale plan that would set the stage for the takeover bid.

Separately, Couche-Tard said it was in exploratory talks with third parties about the potential sale of its U.S. stores to help it gain regulatory approval. (Reporting by Gnaneshwar Rajan in Bengaluru and Anton Bridge in Tokyo; Editing by Mrigank Dhaniwala, Janane Venkatraman and Jamie Freed)