In a letter sent to the environmental group Greenpeace Thursday, a State Department deputy legal adviser writes that Tillerson decided to recuse himself in “early February… from working on issues related to TransCanada's application for a presidential permit for the proposed Keystone XL pipeline."
"He has not worked on that matter at the Department of State, and will play no role in the deliberations or ultimate resolution of TransCanada's application," the letter continues.
The State Department would not say exactly when Tillerson made that decision. He was sworn in as Secretary on Feb. 1, just over a week after President Donald Trump signed an executive order on Jan. 24 to advance the Keystone pipeline’s construction, along with that of the Dakota Access pipeline.
The letter comes in response to one sent by Greenpeace yesterday, which urged the secretary to recuse himself given that his former employer would benefit from the pipeline’s construction. After the receiving the State department's response noting Tillerson's recusal Thursday, Greenpeace responded with an additional statement.
“Rex Tillerson's recusal from the Keystone Pipeline decision might have never been transparent to the public without people flooding the lines of the Office of Government Ethics today," the statement reads. "We must keep pushing this administration into the spotlight and demanding that ethics watchdogs hold these individuals accountable and make these decisions regarding rampant conflicts of interest transparent."
It is unclear whether Tillerson still owns stock in ExxonMobil, but as part of his agreement with the Office of Government Ethics, he must fully divest from the company by May. In briefings on both Tuesday and Thursday, the State Department was asked by ABC News and other reporters whether Tillerson had already divested, but acting spokesman Mark Toner did not provide information on the secretary's status, only to say that "he's working with the Office of Government Ethics."
“As he made clear in his testimony to Congress, he’s committed to federal ethics rules, and he’s continuing to carry out and meet the terms of this agreement." said Toner Tuesday. "I think he has until May 2, I believe, to fully divest."
ABC News' Ben Gittleson contributed to this report.