LOS ANGELES (Reuters) -Hollywood's striking Writers Guild of America (WGA) and SAG-AFTRA actors' union filed a grievance with the National Labor Relations Board (NLRB) against Comcast's NBCUniversal on Tuesday, accusing the company of blocking a picket area.

The unions said NBCUniversal infringed its freedom to picket and endangered its members by obstructing a public sidewalk next to the company's studio lot in California with an ongoing construction project.

NBCUniversal did not immediately respond to a request for comment.

The striking Hollywood actors joined film and television writers on picket lines for the first time in 63 years last week as they demanded higher streaming-era pay and curbs on the use of artificial intelligence.

The WGA's complaint said NBCUniversal "forced picketers to patrol in busy streets with significant car traffic where two picketers have already been struck by a car."

SAG-AFTRA said members had been forced "to picket at the unsafe crowded location, exacerbating the dire public safety situation to interfere with striking members' right to engage in the protected, concerted activity of picketing and patrolling outside the employer's premises during a lawful strike."

Both unions asked the NLRB to order NBCUniversal to remedy the situation.

(Reporting by Mrinmay Dey and Baranjot Kaur in Bengaluru and Lisa Richwine in Los Angeles; Editing by Leslie Adler and Jamie Freed)