The United States has sent food and medicine to Colombia's border with Venezuela, U.S. officials said on Tuesday, although it is still unclear how the aid will get past the objections of President Nicolas Maduro, who has blocked shipments in the past.

Two officials who spoke on condition of anonymity said the aid will be staged at the main Colombian-Venezuelan border crossing at Cucuta. One official said more supplies would be staged in Brazil and in the Caribbean.

"I anticipate having perhaps a dozen locations all around Venezuela where such aid will be staged," the official said.