A two-day summit of American states has ended without agreement on US-led proposals for a free trade area.
The plan was heavily promoted by US President George W Bush but was opposed by other leaders, including the Venezuelan President Hugo Chavez.
Last night Mr Bush left Argentina for Brazil, as the summit broke up without setting a date for the holding of future negotiations on the issue of free trade.
The summit was overshadowed by violent anti-US protests which erupted on the opening day.
Riot police fired tear gas at hundreds of rock-throwing demonstrators who tried to breach the summit's security perimeter. Protesters roamed the streets downtown for some 90 minutes before security forces restored order.
Police said 68 people were arrested and a further eight were detained in Buenos Aires in similar violent protests.
The next Summit of the Americas will be hosted by Trinidad and Tobago. The date has yet to be set, but the gathering is expected to be held in late 2008 or 2009.
