YOKOHAMA, Japan/HONG KONG (Financial Times) -- Hiroto Saikawa, who served as chief executive of Nissan under Carlos Ghosn, has warned that the carmaker has been damaged by Japanese nationalists wanting to unwind its 20-year alliance with France's Renault.

In his final interview before a new chief is installed on Monday, Mr Saikawa said: "There were people inside Nissan who held deeply rooted conservative views that the company should go back to before it faced its financial crisis in the late 1990s. These forces were unleashed when the Ghosn system fell."

Mr Saikawa's last 12 months as Nissan's head have been overshadowed by a historic collapse in profits, suspicions that he led a corporate coup against his chairman, Mr Ghosn, and accusations that he signed off on a retirement package at the heart of allegations against his former boss.

When the board turned against Mr Saikawa in September, it was the findings of overpayments that led to his downfall. Mr Saikawa denies any role in bringing down his former mentor and prior knowledge of any financial misconduct. Mr Ghosn, under house arrest since April and awaiting trial, denies allegations of wrongdoing.

In the months since Mr Saikawa was forced to resign in September, interviews with executives inside Nissan and Renault have illustrated a complex picture of a man who was caught between fierce loyalists to Mr Ghosn and anti-Renault forces inside the Japanese group.

This came as Mr Saikawa attempted to stem the chaos that followed the former chairman's arrest a year ago and stabilise a shaky alliance with Renault.

"Things didn't move forward in the beginning at all because people close to Mr Ghosn resisted and claimed there was a conspiracy," Mr Saikawa said. "Initially it was a very big burden that I couldn't communicate normally with Renault."

Despite all the turmoil at Nissan, Mr Saikawa suggested he was optimistic about the future for the carmaker as a new generation takes over.

Makoto Uchida, head of Nissan's China business, will take over as chief next week, running the company with Ashwani Gupta, chief operating officer at Nissan's partner Mitsubishi Motors, and Jun Seki, who heads Nissan's recovery plan.

"All three... have built their careers after Nissan has internationalised and the alliance is part of their DNA. They know what the issues are [with the alliance] and what they need to do," Mr Saikawa said. "So many unexpected things happened over the past year, but I'm quite relieved that I will be succeeded by this next generation of leaders."

In the weeks ahead of his resignation, Mr Saikawa and Renault chairman Jean-Dominique Senard held talks about how to level the capital structure of the alliance - where Renault owns 43 per cent in Nissan while the Japanese group holds 15 per cent in its French partner - according to people with knowledge of the negotiations.

But there are a variety of external pressures. Nissan is focusing on reviving its business and Renault is selecting a new chief.