(Adds joint statement from Tianqi/Nutrien and details on expanded China-Chile trade deal)
By Antonio De la Jara and Dave Sherwood
SANTIAGO, Oct 25 (Reuters) - Chile's Constitutional Court on Thursday rejected a lawsuit to block Chinese miner Tianqi Lithium Corp's $4.1 billion purchase of a stake in Chilean lithium miner SQM, all but clearing the way for the transaction to close.
In a 3-2 ruling, the court said the lawsuit was "inadmissible" and lifted its suspension of the sale to Tianqi of a 24 percent holding in SQM, the world's No. 2 lithium miner.
In a joint statement, Tianqi and Canadian fertilizer producer Nutrien Ltd, which is selling the stake, said they were "satisfied" with the ruling and would press ahead with completing the sale by the end of the year.
Lawyers for Julio Ponce Lerou's Pampa Group, which is SQM's majority shareholder, did not respond to a request for comment.
Lithium has become one of the world’s most in-demand commodities because of the rising popularity of electric vehicles powered by lithium-ion batteries.
The initial lawsuit, brought by Ponce, was intended to scuttle an agreement struck between Chile's antitrust regulators and Tianqi.
Ponce's lawyers argued the deal had been struck "practically in secret" and that it failed to protect SQM's corporate secrets from top competitor Tianqi.
Nutrien must sell its SQM shares by April 2019 in order to comply with regulatory requirements put in place by Indian and Chinese authorities following a prior merger.
The court's decision is final and not subject to appeal, but one legal hurdle remains. Pampa filed an additional appeal earlier this month with Chile's antitrust court.
Nutrien previously argued that the "real objective" of Ponce's legal maneuvers was to block the sale to Tianqi and force Nutrien to "miss its deadline with Indian and Chinese regulators."
Pampa said it was concerned that Tianqi, which controls Talison Lithium, a joint venture with No. 1 lithium producer Albemarle Corp in Australia, could share secrets with its U.S.-based competitor and neighbor in Chile's lithium-rich Salar de Atacama.
Tianqi's bid to acquire the stake comes as Beijing aggressively promotes electric vehicles to combat air pollution and help China's domestic carmakers build global brands.
Also on Thursday, Chile's foreign minister celebrated the signing of a free trade deal with China that will streamline customs controls and widen access to the Chinese market for Chilean products, including from its critical forestry industry.
Foreign Minister Roberto Ampuero, who will travel to Beijing and Shanghai next week, said in a communique that his country's relationship with China was "key." (Reporting by Antonio de la Jara and David Sherwood; Editing by Sandra Maler and Peter Cooney)