South Wales Police have arrested two men in Cardiff for inciting criminality through social networking website Facebook.
They were arrested as part of an ongoing police investigation into the public order incidents in Cardiff overnight on Tuesday.
Gwent Police urged people to use social media responsibly and not fuel rumours, according to the BBC.
South Wales Police is continuing to monitor social networking sites. Anyone who uses social media to attempt to generate disorder will be traced and dealt with, a spokesman said.
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Deputy chief constable of Gwent Police, Jeff Farrar, said the irresponsible use of social media has caused unnecessary fear and anxiety in the community.
"We have already made arrests and will continue to do so. We want people to know that we not only police the streets in Gwent, we police the online community as well," Farrar said.
Home secretary Theresa May will be meeting with Facebook, RIM and Twitter to discuss the role of social media in the riots, but the Home Office said no more details were currently available.
Jim Killock, director of campaign body the Open Rights Group, warned that government should not use pre-emptive measures to shut down communication tools.