PARIS: Renault-Nissan has not decided whether to publish figures on  cost savings and other synergies achieved by the alliance over the last year, as has been its custom, two sources close to Renault said, amid growing tension in the partnership.

Over the past decade, the group has released figures each summer detailing how much money has been saved through cost-cutting, production sharing and other efficiencies, establishing it as a barometer of the health of the 20-year-old alliance.

But since Carlos Ghosn, the former group chairman, was arrested in Japan and charged with corruption, relations between Renault and Nissan have frayed, raising doubts about the future of the one of the more successful auto alliances.

"People have changed, governance has changed, why go on doing exactly the same thing," one of the sources told Reuters, referring to the annual synergy figures.

"We haven't taken a definitive decision (on whether to publish it)."

The last cost-saving announcement, approved by the management of each company, was made in June 2018 and detailed synergies of 5.7 billion euros ($6.4 billion) achieved in 2017.

That was up from 5 billion euros in 2016, 4.3 billion euros in 2015, 3.8 billion euros in 2014 and 2.9 billion euros in 2013. The figures were first published in 2010.

The target for 2018, according to the last forecast published before the Ghosn affair, was for cost-savings and revenue gains totalling 5.5 billion euros, slightly down on 2017.

The long-term objective was to hit 10 billion euros by 2022-2023 -- out of total annual revenue, with Mitsubishi having joined the alliance in 2017, of around 170 billion euros.

Renault is due to publish its first half earnings on July 26.