Mr Lula has said that the "climate of unease" in Latin America disturbs him
Brazil's leader has called on US President Barack Obama to meet South American leaders to calm fears about the US military presence in Colombia.
Luiz Inacio Lula da Silva expressed his concerns in a phone call to President Obama, Brazil's foreign minister said.
He wants guarantees that US troops will be restricted to fighting drugs and terrorists within Colombia only.
The US and Colombia are finalising an agreement to give the US military greater access to seven bases.
'Winds of war'
Brazil's Foreign Minister Celso Amorim said President Lula told Mr Obama it was "very important" that he attend a South American summit in Argentina starting next Friday.
The Unasur meeting has been specifically called to address the Colombian bases issue.
On Tuesday, US Secretary of State Hillary Clinton tried to calm fears by saying the US would not establish its own bases and would not increase troop levels in Colombia, where 800 US soldiers and 600 US contractors are already based.
Mrs Clinton said the accord would respect Colombian sovereignty and other countries would not be affected.
Venezuela and Ecuador had expressed fears the move amounted to preparation for an invasion of their countries by US forces.
Venezuelan President Hugo Chavez warned that "the winds of war were beginning to blow" across the region.