FILE PHOTO: Facebook logos are seen on a mobile phone in this picture illustration taken December 2, 2019. REUTERS/Johanna Geron/Illustration

SAN FRANCISCO (Reuters) - Four companies sued Facebook Inc FB.O in U.S. federal court on Thursday for alleged anticompetitive conduct, saying the social network inappropriately revoked developer access to its platform in order to harm prospective competitors.

The plaintiffs sought class-action status and unspecified damages, according to a filing at the U.S. District Court for the Northern District of California.

“Facebook faced an existential threat from mobile apps, and while it could have responded by competing on the merits, it instead chose to use its might to intentionally eliminate its competition,” said Yavar Bathaee, a partner at law firm Pierce Bainbridge and co-lead counsel in the case.

Facebook indicated that it would fight the lawsuit.

“In the current environment, where plaintiffs’ attorneys see financial opportunities, claims like this aren’t unexpected but they are without merit,” a Facebook spokesperson said in an email statement.

The filing is an escalation of Facebook’s battles with small app developers that had built companies based on access to its user data. Facebook cut off access for certain apps as far back as 2012, while still allowing access for others.

Thousands of pages of damaging internal emails have emerged from a similar lawsuit filed by Six4Three, the developer of a now-shuttered bikini photo app. Facebook has described the Six4Three case as baseless.

The social network also faces multiple investigations into possible antitrust violations by regulators around the world.