MANAMA, Bahrain — Bahrain's main opposition group says the kingdom's paramilitary National Guard is deploying to back up police as authorities try to quell rising political violence.

Wider use of the Guard could signal a tougher strategy by Bahrain's embattled Sunni monarchy as riot police struggle to contain the Shiite majority's 21-month uprising.

Hadi al-Musawi, a spokesman for Al Wefaq, says Guard troops were seen Saturday setting up in Sitra, a center of the revolt. Previously, Guard forces — separate from the regular military — have been used mainly at key sites in the capital, Manama.

Heavy clashes erupted Saturday after the funeral of a teenager killed in a traffic incident during a clampdown on marchers the day before.

More than 55 people have died in Bahrain's unrest.