The arrest of a New Yorker for using Twitter to alert protesters to police movements at a meeting of world leaders in Pittsburgh last month would be deemed a human rights violation if it happened in Iran or China, rights activists charge.

Pittsburgh police arrested Elliot Madison, 41, on September 24 as hundreds of people -- some throwing rocks and breaking shop windows -- protested on the first day of a summit of the Group of 20 rich and developing nations.

The protesters, with a broadly anti-capitalist agenda, were kept well away from the convention site where the leaders held their two-day meeting. Police sporadically used pepper gas to disperse them.