Top Nikkei executives on Friday vowed to respect the Financial Times' editorial independence after its surprise $1.3 billion takeover raised fears about the Japanese media giant's plans for the prestigious paper.

"We have no intention of changing the content or form of the Financial Times," Tsuneo Kita, the Nikkei's chairman, told reporters at a press briefing in Tokyo.

Naotoshi Okada, the Japanese business bible's chief executive, added: "We're going to preserve editorial independence... that is what we've told (them)".

The unlikely cross-border marriage announced Thursday has sparked concerns about interference from the new owners at the storied salmon-pink business paper, which was founded in 1888.

Those fears were amplified by comments from Japan's economy minister Akira Amari, who said the deal would translate into "more accurate" stories about his country to an international audience.

Japanese media are routinely criticised as timid in pursuit of investigative news, raising fears that the Nikkei's tendency to shy away from criticising big business could affect future FT stories.

"I'm worried that the Financial Times could become like the Nikkei, and I hope that will not be the case," said Goushi Kataoka, an economist at Mitsubishi UFJ Research.