PARIS (Reuters) - A senior Renault-Nissan executive has quit the troubled carmaking alliance to join Peugeot maker PSA Group PEUP.PA, blaming Renault boss Thierry Bollore for forcing his exit.

FILE PHOTO: Arnaud Deboeuf leaves after the Renault-Nissan-Mitsubishi alliance meeting, in Amsterdam, the Netherlands, November 29, 2018. REUTERS/Piroschka van de Wouw/File Photo

Former alliance director Arnaud Deboeuf will become PSA's industrial strategy director under Chief Executive Carlos Tavares, himself a former Renault RENA.PA second-in-command, the rival French carmaker confirmed on Tuesday.

Deboeuf’s departure underscores deep tensions threatening to subsume the Renault-Nissan alliance in the wake of the November 2018 arrest of former Chairman Carlos Ghosn, now awaiting trial in Japan on financial misconduct charges he denies.

Those tensions have been exacerbated by failed attempts under Bollore and new Renault Chairman Jean-Dominique Senard to secure a full Renault-Nissan merger and to combine Renault with Fiat Chrysler (FCA), a move thwarted by France.

Deboeuf was well regarded at Nissan and even offered a senior executive role at the Japanese carmaker, as his relations with Bollore soured following Ghosn’s ouster, three sources told Reuters. But Bollore, a former Ghosn protégé who succeeded his absent boss as CEO in January, blocked the move.

“Thierry Bollore told me no one wanted to work with me ... and that I could not go to work at Nissan either,” Deboeuf said in a farewell email to colleagues seen by Reuters.

Renault declined to comment on Deboeuf’s departure. Deboeuf did not respond to requests for comment.

Since FCA deal talks collapsed in June, Nissan has pressed Renault to cut its 43.4% stake in the Japanese carmaker as the price of its support for a revived FCA tie-up.

Renault is refusing to consider cutting its holding below a 33% blocking minority, and no agreement is yet in sight, according to two people closely following Renault-Nissan talks on the future of the alliance.

One option being discussed is a smaller immediate stake cut and an agreed mechanism to deliver a deeper reduction in future, if key milestones are met, one of the sources told Reuters.

Shares in Nissan, hit by a sales slump since Ghosn’s exit, are trading 35% below their value before his Nov. 19 arrest. The stock rose 1.3% on Tuesday, with Renault advancing 1% on reports that the alliance talks were progressing.

Deboeuf’s move adds to a steady Renault brain-drain to PSA since 2013, when Tavares was hired to rescue the carmaker from near-bankruptcy.

Other switchers from Renault include Yann Vincent, PSA’s executive vice president for manufacturing, powertrain engineering chief Alain Raposo. Thierry Koskas joined PSA as sales chief in March, two months after Bollore ousted him from the same role at Renault.

Tavares, who preceded Bollore as Ghosn's No.2 at Renault, was pushed out after publicly voicing CEO ambitions. Under its Portuguese-born leader, PSA has set new profitability records while making swift headway on the integration of Opel, acquired from General Motors GM.N in 2017.