(Reuters) - U.S. activist shareholder Nelson Peltz has in recent weeks been building up stakes in PepsiCo Inc and Oreo maker Mondelez International Inc , Britain's Daily Telegraph reported on Friday, citing sources familiar with the matter.

The newspaper said the exact size of Peltz's stakes in the two companies were unclear, but cited one source as saying that Peltz had spent at least $2 billion in a concerted buying spree.

According to a February 14 regulatory filing, Peltz's Trian Fund Management did not hold any stock in either company as of December 31, 2012.

PepsiCo and Trian Fund Management were not immediately available for comment.

A spokesman for Mondelez said he was not aware if Peltz had a stake in the company.

(Reporting by Karen Rebelo in Bangalore; Editing by Chris Gallagher)