Venezuelan President Hugo Chavez, a fierce critic of the United States, slammed "very bad signals" from US president-elect Barack Obama that he said were "disrespectful" to Iran.

"Iranian President Mahmoud Ahmadinejad sent him a letter. The reply wasn't good. It was disrespectful. Obama was unable to get away from the cliche. He spoke like (President George W) Bush. They are very bad signs," Chavez said in a late night news conference to foreign journalists.

Obama told his first news conference after winning the US presidential election on November 4 that Iran's pursuit of nuclear weapons was "unacceptable."

He also said that he would "respond appropriately" to a congratulatory letter from Ahmadinejad. Chavez has tense relations with the United States, despite being one of its main suppliers of crude oil.

Venezuela expelled the US ambassador to Caracas in September and Washington responded in kind. Chavez said that the United States is "the empire that kills, bombs and assassinates. If Obama can convert that infernal machine into a machine that benefits the world, I think that would be a lot to hope for".

"We only aspire to respect. Hopefully he'll surround himself with good advisors, that he honours his colour, his origin that he remembers where he comes from. His wife is black, what beautiful children they have," the fierce leader said.

"Hopefully they're not going to kill Obama, but that murdering machinery is capable of anything," Chavez added.