The Japanese owner of convenience store chain 7-Eleven has rejected a $38bn (£29.2bn) takeover bid from a Canadian rival.

In a letter addressed to the Circle K owner Alimentation Couche-Tard (ACT), Seven & i Holdings said the Canadian company’s offer “grossly” undervalued the company and was fraught with regulatory risk.

The 7-Eleven owner added, however, that it remains open to negotiations and ready to consider a better proposal.

ACT did not immediately respond to a BBC News request for comment.

“The Special Committee believes that your proposal is opportunistically timed and grossly undervalues our standalone path and the additional actionable avenues we see to realize and unlock shareholder value,” said the letter sent by Stephen Dacus, the chair of the Seven & i special committee of independent directors that was formed to consider the offer.

The letter also disclosed that the initial offer by ACT valued Seven & i at $14.86 per share. That’s more than 20% over its share price before the offer was announced.

ACT’s offer comes at a time of significant weakness in the Japanese yen against the US dollar, making Seven & i more affordable to foreign buyers.

“Your proposal does not adequately acknowledge the multiple and significant challenges such a transaction would face from US competition law enforcement agencies,” Seven & i’s letter added.

7-Eleven is the world’s biggest convenience store chain, with 85,000 outlets across 20 countries and territories.

Quebec-based ACT is listed on the Toronto Stock Exchange and runs around 17,000 shops in more than 30 countries and territories across North America, Europe and Asia under the Circle K and Couche-Tard brands.

ACT’s footprint in the US and Canada would more than double to about 20,000 sites were a deal to go ahead.

If successful the buyout would be the largest ever foreign takeover of a Japanese firm and create a 100,000-strong global convenience store giant.