The Obama administration is denouncing Venezuelan President Hugo Chavez for questioning whether the U.S. might be behind a rash of cancer cases among Latin American leaders.

The State Department on Thursday said Chavez's comments were "horrific and reprehensible." Spokeswoman Victoria Nuland said they were not worthy of further response.

Chavez has long questioned whether the U.S. government could be plotting to oust him. But earlier this week he went far beyond that, saying it was very strange that he and the leaders of Argentina, Brazil and Paraguay have struggled with cancer.

He said he was not accusing the U.S. and does not have any proof. But he asked, in his words, "Would it be strange if they had developed a technology to induce cancer and no one knew it?"

Brazilian President Dilma Rousseff overcame lymphoma in 2009, and former president Luiz Inacio Lula da Silva is being treated for throat cancer. Paraguayan President Fernando Lugo was diagnosed with lymphoma last year. Chavez underwent surgery for a tumour last summer.

All the leaders are considered to the left of the political spectrum, with policies aimed at reducing poverty. But Chavez — who has overseen the nationalization of Venezuela's oil and gold production, among other measures — is by far the most vocal critic of the U.S.

With files from CBC News