(Reuters) - Tyson Foods (>> Tyson Foods, Inc.), the largest U.S. meat processor, said on Thursday it slightly raised its stake in plant-based protein maker Beyond Meat as it looks to tap growing demand for alternative sources of protein.

The company, which already owns a 5 percent stake in Beyond Meat, said it participated in the most recent funding round through its venture capital fund. Details of the investment were not disclosed.

California-based Beyond Meat sells plant-based burger patties, heat-and-eat meals and non-GMO soy and pea protein frozen foods at grocery chains such as Amazon.com Inc's (>> Amazon.com) Whole Foods Market, Publix and Albertsons Cos Inc's (>> Albertsons Companies Inc) Safeway.

Traditional meat sales have come under pressure on growing concerns about animal welfare and the environmental impact of intensive animal farming, apart from a rising perception of vegetarian meals as healthier.

U.S. companies such as Beyond Meat and MorningStar Farms, owned by the world's largest cereal maker, Kellogg Co (>> Kellogg Company), are leading the charge in the meat substitute market.

The industry could reap $5.2 billion in sales by 2020, according to Oregon-based Allied Market Research (AMR), an 8.4 percent rise from 2015.

(Reporting by Uday Sampath in Bengaluru; Editing by Anil D'Silva)