By Abigail Summerville and Svea Herbst-Bayliss

New York, Dec 12 (Reuters) - Post Holdings Post.n Is Working With Investment Bankers to Explore a Possible Transaction With Lamb Weston Holdings Lw.n, as the Frozen Potato Products Maker Faces Pressure From an Activist Investor to Sell Itself, Two Sources Familiar With the Matter Said.

For Packaged Goods Company Post, Which Makes Grape Nuts Cereal and Bob Evans Mashed Potatoes, Lamb Weston Has Long Been an Attractive Business That It Considered Buying in 2015 When the French-Fry Maker Was Still Part of Conagra Cag.n.

Now Post Is Again Exploring Ways to Own Lamb Weston and Is Consulting With Bankers in the Tight-Knit Food Industry, Said the Sources Who Insisted on Anonymity Because the Discussions Are Private.

Post Has a Market Value of Roughly $7 Billion and the Sources Said There Would Be Considerable Synergies With Lamb Weston, Which Has a Market Value of Roughly $10.5 Billion, if a Combination Were to Occur.

A Representative for Post Declined to Comment While a Representative for Lamb Weston Was Not Immediately Available for Comment.

(Reporting by Svea Herbst-Bayliss and Abigail Summerville; Editing by Chizu Nomiyama)

((Svea.herbst@Thomsonreuters.com; +617 233 2138; Reuters Messaging: Svea.herbst.thomsonreuters.com@Reuters.net))