WASHINGTON — The Justice Department is investigating whether Comcast Corp. and other cable companies are violating antitrust laws by limiting competition from Internet video providers, two people familiar with the matter said.

The department is examining whether Comcast and Time Warner Cable Inc. are using their status as providers of programming and high-speed Internet to put online video providers such as Netflix Inc. and Hulu LLC at a competitive disadvantage, said the people, who weren’t authorized to speak publicly.

Authorities are probing whether Comcast broke the law by creating incentives to consumers to watch programming through its cable services instead of through the online video providers, the people said.

The department also is reviewing whether cable companies signed deals to obtain television programming at lower prices than online providers are charged, the people said. Such agreements may violate the law, they said.

Comcast and other cable companies are finding questionable ways to quash competition from video providers, said Mark Cooper, director of research at the Washington-based Consumer Federation of America.

Without low-cost access to online video, “consumers will suffer in the long term,” said Cooper. “Prices will be higher and choices will be fewer” for programming, he said.

Jennifer Khoury, a spokeswoman for Comcast, and Alex Dudley, a spokesman for Time Warner Cable, declined to comment.

The Justice Department and the Federal Communications Commission have said they want to foster the growth of online video to provide consumers more viewing choices.

Before approving the purchase of NBC Universal last year, the government imposed conditions on Comcast to ensure the company wouldn’t unfairly compete against online video companies.