MILAN, Dec 15 (Reuters) - Eni is in discussions with funds interested in buying a minority stake in the Italian energy group's Novamont unit in a deal that could value the bioplastic maker at around 1 billion euros ($1.1 billion), a source close to the matter said.

Eni added Novamont to its chemical division earlier this year, by acquiring in October the 64% of the company it did not already own from private equity funds Investitori Associati II and NB Renaissance for an undisclosed price.

Teaming up with an investor could now help Eni grow Novamont more quickly, improving the sustainability credentials of its entire chemical business by increasing its exposure to the circular economy sector.

Piedmont-based Novamont, which Eni owns through its chemical unit Versalis, is the world's leader in the production of bioplastics.

The source said that investors interested in the potential deal included Norway's private equity fund HitecVision and U.S. fund Blackstone.

The discussions with potential investors are at a preliminary stage and Eni has taken no final decision on the size of the stake it could sell.

Eni and Blackstone declined to comment on the issue. HitecVision did not immediately respond to a request for comment.

Unlike regular plastics, which are mostly made from fossil fuels and accumulate in the environment, bioplastics are made from natural or renewable sources and can be biodegradable.

Novamont holds more than 1,400 patents and patent applications. One of its main products is MATER-BI, a group of biodegradable and compostable bioplastics, which are derived from starches, cellulose, vegetable oils and their combinations.

The source said that Italian bank UniCredit was advising Eni over Novamont. UniCredit declined to comment. ($1 = 0.9088 euros) (Reporting by Francesca Landini and Valentina Za; Editing by Susan Fenton)