* Keller, new board had differences of vision, style
* Opposition says Keller's departure politically motivated
* Interim CEO to be named on June 13
(Adds background on Codelco, details)
SANTIAGO, June 6 (Reuters) - Chilean state-run copper miner Codelco said it was removing Chief Executive Officer Thomas Keller to seek new leadership at a pivotal time for the company, but opponents said the decision was politically motivated.
Keller, a former retail executive, has earned plaudits for his efforts to overhaul old mines and cut costs at the world's No. 1 copper producer, but his tough style triggered tensions with Codelco's powerful unions and the new center-left government.
The board stressed the removal of Keller, seen as close to the right, was not politically motivated, while the conservative opposition decried what it said was meddling that could harm the miner in the midst of an ambitious investment plan.
"We asked Thomas Keller to tender his resignation as CEO as a result of the company's move towards a new phase with new challenges that require new leadership," new board head Oscar Landerretche told journalists after a more than five-hour meeting that ended early Friday morning.
The board voted 5-3, with one abstention, to remove Keller.
"There were no arbitrary political motivations, though there were motivations surrounding the company's politics, the politics of what Codelco should be in the future," Landerretche said. " ... There was no single factor that formed board members' opinion."
Keller took the reins of the company in 2012, during the conservative administration of Sebastian Pinera.
Current center-left President Michelle Bachelet, whose term began in March, tapped three new directors to the board, including Landerretche.
Keller, who had said he had different views from the board on how to run the company, ruffled some feathers with a sometimes brash personal style.
NO OBVIOUS CANDIDATE
There is no obvious candidate to become Codelco's next CEO. Keller's successor will face major challenges, including overseeing a multibillion-dollar plan to overhaul the company's massive mines, cutting costs and negotiating with unions.
Codelco hopes to name a new CEO within months, said Landerretche, an economist and key architect of Bachelet's tax reform plan. The board will probably seek a more union-friendly CEO to help navigate controversial redesigns of some of Codelco's aging mines.
"We will probably accept applications," Landerretche said. "We need to find someone who has the knowledge and experience to lead the huge, diverse and challenging portfolio of major projects that Codelco is facing."
Much of Chile's copper was nationalized in the 1970s and has proved a crucial motor of development, but political involvement in Codelco has been an issue.
Bachelet, a moderate, was instrumental in giving Codelco's board more autonomy during her first term as president. The mining industry will look hard at the new CEO for any signs Codelco is being "politicized."
The conservative opposition said that had already happened.
"(The) removal of Codelco's CEO Thomas Keller is a political and imprudent decision," Francisco Orrego, deputy mining ministry under Pinera, said in a tweet. "(The) company's corporate (governance is) at stake."
(Reporting by Alexandra Ulmer; Editing by Lisa Von Ahn)