BOGOTA, Colombia (AP) -- Thousands marched through the streets of Colombia's capital and another city on Thursday, protesting a planned trade agreement with the United States which they fear would worsen unemployment in Colombia.

As trade negotiators from Peru, Colombia, Ecuador and the United States met for a new round of talks in the resort city of Cartagena on Colombia's Caribbean coast, some 5,000 people marched toward the city's convention center where the talks were held, but police kept them away from the venue. No violence was reported.

About as many protesters, including opposition lawmakers, students and government workers, took to the streets of the capital, Bogota, also protesting the planned deal.

"This is a democratic and peaceful exercise to demonstrate our concerns over the loss of jobs due to a free trade deal," Carlos Rodriguez, a protest organizer and president of Colombia's umbrella trade union, CUT, told The Associated Press.

Negotiations for the free trade began in May 2004, but differences over agriculture and intellectual property have delayed the treaty's signing. Andean growers of sugar cane, rice, corn, potatoes and cotton say they won't be able to compete against heavily subsidized U.S. goods.

Rodriguez estimated that in Colombia alone some 250,000 jobs would be lost if a free trade deal is signed, most of them in the agriculture sector. Colombia's jobless rate is currently 12 percent, and 60 percent of the country lives below the poverty line.

The three Andean nations already enjoy duty-free access to U.S. markets, selling thousands of products like asparagus, cut flowers and clothing. But those breaks -- given to help reduce economic dependence on drug production and trafficking -- expire next year.

Colombian officials say they hope to sign the free trade deal in October or November. Each country would then need to ratify the treaty.

In downtown Bogota, Thursday, a protester walks with an umbrella underneath a Colombian flag.