Venezuelan President Hugo Chavez arrived in Tehran late on Saturday for the third time during the presidency of Mahmoud Ahmadinejad, a fellow fiery critic of the US, Iranian television reported.
Chavez, accompanied by his foreign, communication, energy, industry and economy ministers, was met at the airport by Iranian Industries Minister Ali-Reza Tahmasbi, the television said.
During the two-day visit, the last leg of a tour that has taken Chavez to Russia and Belarus -- both recently at loggerheads with the US -- he will hold talks with top Iranian officials and discuss bilateral, international and regional issues, Iranian media said.
Iran is OPEC's fourth-largest crude producer while Venezuela is also a major player in the cartel, and the two countries enjoy warm ties in the energy sector.
During the visit, the countries are expected to sign a number of agreements including for the construction of 7,000 houses, a petrochemical plant and a vocational training center in Venezuela.
Venezuelan Ambassador to Tehran Arturo Anibal Gallegos Ramiraz told the official IRNA news agency that Chavez's visit was "aimed at bolstering mutual cooperation in economic, industrial and political fields."
"Iran and Venezuela through exchange of visits can prove that their relations are at the best possible level," he said.
Chavez is the most vocal cheerleader in Latin America for Iran and its nuclear program, which is feared by the West to be a cover for weapons development.
The trip comes at a time when Iran is threatened with toughened UN Security Council sanctions for its continued refusal to freeze controversial nuclear work.
The US, which broke diplomatic ties with Iran in 1979, has been spearheading the international campaign to stop Iran's enrichment program and it has never ruled out ruled out a military option to halt the drive.
Chavez is expected to visit the land-based facilities of Iran's South Pars gas field in Asaluyeh off the Gulf coast and speak at Tehran's Science and Industry University, where Ahmadinejad used to teach before being elected president in 2005.
Ahmadinejad toured Latin America in January in a bid to seek support from the region's leftist leaders who share his scornful defiance of the US.
Venezuela and several other Latin American countries are members of the Non-Aligned Movement that at a summit last year emphatically backed Iran's right to nuclear energy.
As Iran's No. 1 ally, Venezuela was alone in September 2005 in opposing a resolution at the International Atomic Energy Agency that found Iran in violation of nuclear safeguards, paving the way for its referral to the Security Council.
During his latest trip, which kicked off on Wednesday, Chavez met with Russian President Vladimir Putin and Belarus counterpart Alexander Lukashenko and urged a global revolution against Washington.
He has also discussed possible purchases of submarines and other defense equipment from Russia, arguing that these are needed to defend his oil-rich country against the US.