ZURICH  - Clariant Chief Executive Ernesto Ochiello has quit after just 10 months, an abrupt move that comes as the Swiss specialty chemicals maker negotiates with 25% stakeholder Saudi Basic Industries (SABIC) over the future of a key business area.

Hariolf Kottmann, the former CEO and current chairman, will assume leadership duties on an interim basis until a successor is found, the Muttenz-based company said on Wednesday. Clariant gave few specifics, saying Ochiello was leaving "for personal reasons, with immediate effect".

Ochiello, a former manager at Saudi Arabia's SABIC, had taken over Clariant's helm last September when Kottmann became chairman.

Clariant, which is unloading businesses including Medical Specialties to focus on faster-growing units, is in talks with SABIC over the creation of a High Performance Materials unit. The joint venture aims to combine Clariant's additives and specialty masterbatches businesses with parts of SABIC's specialty chemicals operation.

"Clariant will continue to implement its strategy," Kottmann said in a statement, adding he would provide details on the talks with SABIC on Thursday when it releases first-half 2019 results.

Ochiello's abrupt departure marks a return to uncertainty at Clariant that has buffeted the company over the last two years. A dispute between the Swiss company and U.S.-based activist investor White Tale scuttled a planned merger with U.S.-based Huntsman Corp. in 2017, in a drawn-out conflict only ended when SABIC bought its 25% stake in January 2018.

(Reporting by John Miller, editing by Riham Alkousaa) ((J.Miller@thomsonreuters.com; +41 58 306 7734; Reuters Messaging: j.miller.thomsonreuters.com@reuters.net))