Japanese companies cannot use a national security designation as a tool to thwart foreign takeovers, a senior Finance Ministry official said, pushing back at speculation Tokyo's foreign exchange act could be manipulated for protectionism.

The comments follow media reports retail giant Seven & I Holdings is seeking to be classified as "core" to national security under the Foreign Exchange and Foreign Trade Act (FEFTA) to fend off a buyout bid from Canada's Alimentation Couche-Tard.

The senior official, who declined to comment on individual deals, said the issue of "core" classification doesn't change the process of the government's security review in cases of foreign bids for companies designated as significant to Japan's economy or security.