More cases of "peace activists gone violent"...but with monks?

I couldn't make this up if I tried. From the Washington comPost:

An anti-violence demonstration in Colombo, Sri Lanka went Jerry Springer, Thursday, when hard-line monks stormed the stage of their pro-peace brethren. First the speaker and a hardliner went at it, punches were exchanged, and then it was on, with robes, fists, and monks flying across stage. The "peace protest" had been organized to find non-violent solutions to the 20 year civil war between Buddhists and Tamil Tiger rebels; and since today's brawl consisted mostly of Buddhist on Buddhist violence it sounds like they're moving in the right direction.

I'm confessing my ignorance here: what is a "hard-line monk"?