WASHINGTON - Alphabet Inc's Google, Facebook Inc and Twitter Inc will testify next week before a U.S. Senate panel on efforts by social media firms to remove violent content from online platforms, the panel said in a statement on Wednesday.

The Sept. 18 hearing of the Senate Commerce Committee follows growing concern in Congress about the use of social media by people committing mass shootings and other violent acts. Last week, the owner of 8chan, an online message board linked to several recent mass shootings, gave a deposition on Capitol Hill.

The hearing "will examine the proliferation of extremism online and explore the effectiveness of industry efforts to remove violent content from online platforms. Witnesses will discuss how technology companies are working with law enforcement when violent or threatening content is identified and the processes for removal of such content," the committee said.

Facebook's head of global policy management Monika Bickert, Twitter public policy director Nick Pickles and Google's global director of information policy Derek Slater are due to testify.

Facebook and Google both confirmed they will participate but declined to comment further. Twitter did not immediately comment.

In May, Facebook said it would temporarily block users who break its rules from broadcasting live video. That followed an international outcry after a gunman killed 51 people in New Zealand and streamed the attack live on his page.

Facebook said it was introducing a "one-strike" policy for use of Facebook Live, a service which lets users broadcast live video. Those who broke the company's most serious rules anywhere on its site would have their access to make live broadcasts temporarily restricted.

Facebook has come under intense scrutiny in recent years over hate speech, privacy lapses and its dominant market position in social media. The company is trying to address those concerns while averting more strenuous action from regulators.