By Milana Vinn and Rishi Kant

Dec 19 (Reuters) - Buyout firm TPG is in advanced talks to buy the fiber unit of tower operator Crown Castle for about $8 billion, a person familiar with the matter said.

Shares of the Houston, Texas-based Crown Castle were up 2.1% in trading after the bell.

A deal for the fiber and wireless units could be announced within weeks, the source said.

However, the source added that while no final decision has been made, the discussions could fall through or another buyer could emerge.

The development was first reported by Bloomberg News.

TPG, along with fiber network owner Zayo Group, was vying for Crown Castle's fiber and wireless assets, Reuters had reported in October, citing people familiar with the matter.

If the talks are successful, the deal would come at a time when mergers are heating up in the fiber industry.

With the rapid growth of fiber broadband boosting business for infrastructure providers such companies such as Crown Castle are being seen as attractive acquisition targets.

Spokespersons for TPG and Crown Castle declined to comment.

The development comes at a time when Crown Castle has been exploring options for its fiber assets, after reaching a deal with activist investor Elliott Investment Management over shaking up its board.

Crown Castle co-founder Ted Miller had told Reuters in February that the company could fetch as much as $15 billion by selling its fiber assets if it let him and his partners join its board of directors.

(Reporting by Rishi Kant in Bengaluru and Milana Vinn in New York; Editing by Shreya Biswas)

((Rishi.Kant@thomsonreuters.com;))