Asked about the potential for joining forces with the rival project CEO Charles Woodburn told reporters on a call on Friday: "I wouldn't rule out one thing or another at the end of the day. These are political decisions."
He also said three partners was enough.
"Yes, it is enough partners, but the door is not closed to others and ultimately, these will be political decisions," he said.
(Reporting by Sarah Young, Editing by Kylie MacLellan)