Hundreds of activists from across Latin America are beginning a series of closed-door strategy sessions before this week's Summit of the Americas following a rocky encounter marked by Cuban government supporters heckling a group of dissidents.

The activists meeting Thursday are putting together proposals to present to President Barack Obama and some 30 other hemispheric leaders at the summit starting Friday on topics ranging from environmental protections to support for democracy in the region.

Organizers fear the grassroots group's work is being politicized after dissidents from the communist-run island attending Wednesday's session were pushed around to shouts of "mercenaries" and "terrorists" by government supporters from Cuba and its ally Venezuela.

The U.S. State Department condemned what it said was "harassment" and "use of violence" against participants.