Top shareholder Vodafone agreed to sell a chunk of Vantage to a consortium including U.S. private equity giants KKR and Global Infrastructure Partners in November. UniSuper said on Monday it was buying into the consortium through KKR.

"We are always looking to doing meaningful-sized stakes, as we're getting to being quite a big fund nowadays," said Sandra Lee, head of private markets at UniSuper, which manages about A$115 billion in assets.

"It wasn't an auction process, and they were looking for larger-scale investors - we were buying into it in an opportunistic style deal."

KKR and GIP had no immediate comment. UniSuper did not disclose any further deal terms. Vantage Towers is due to be de-listed on May 9.

($1 = 1.4765 Australian dollars)

(Reporting by Tom Westbrook and Rae Wee in Singapore; Editing by Jamie Freed)