US Secretary of State Hillary Clinton promised on Wednesday that the United States will use the Internet and social media in its fight against al-Qaida and other extremist groups.

The outgoing top diplomat said the US State Department had "started two organizations to deal with countering violent extremism" on the Internet, and will use tools such as the Twitter micro-blogging site to combat online anti-Americanism.

"Social media is a great tool," Clinton told lawmakers when speaking to Congress about the deadly attack on a US mission in Benghazi, Libya, four months ago.