Iran's new chief nuclear negotiator, Saeed Jalili, made the allegation in comments to visiting Turkish Foreign Minister Ali Babacan, whose country may soon send troops to hunt down Kurdish guerrillas in northern Iraq.Tehran says the rebels are operating in Iraq with U.S. forces present in the country and this shows Washington is refraining from tackling them.
Like Turkey, Iran also has faced cross-border attacks by Kurdish rebels and has shelled targets inside Iraq in response.
"Escalation of terrorism in the region is one of the direct results of the presence of occupiers in Iraq, particularly America," Jalili, an ally of Iranian President Mahmoud Ahmadinejad, said according to the country's state broadcaster.
"And there are documents and information available proving America's support for terrorist groups in the region," he said, without giving details. Jalili is also the new secretary of Iran's Supreme National Security Council.
The United States often accuses Iran of backing and training militias responsible for some of the bloodshed threatening to tear Iraq apart. Tehran denies the charge and blames the violence in Iraq on the presence of U.S. forces.
The two countries are also locked in a stand-off over Tehran's nuclear programme, which Western powers suspect is aimed at developing bombs. Iran says it only wants to generate electricity.
Washington last week dubbed Iran's Revolutionary Guard Corps a proliferator of weapons of mass destruction and accused its Qods force of backing terrorists. It also imposed sanctions on more than 20 Iranian companies, major banks and individuals.
At a joint news conference with Babacan, Iranian Foreign Minister Manouchehr Mottaki on Sunday also accused the United States and Israel of involvement in terrorism in the region.
"We see ... their hand behind some of the regional terrorist activities," Mottaki said.
Babacan, whose country's ties with the United States have deteriorated sharply in recent weeks, thanked Iran for helping Turkey fight the PKK guerrillas and said the two sides had talked about continuing their cooperation.
The Kurdistan Workers Party (PKK) launched its campaign for a Kurdish homeland in southeastern Turkey in 1984. More than 30,000 people have been killed in the conflict since then.
Jalili on October 20 replaced Ali Larijani as Iran's chief nuclear negotiator, a move analysts saw as signalling a toughening of Tehran's position in the atom row.