Iran accused the United States today of a "massacre" of the Iraqi people and said further talks with Washington about improving security in its neighbour would be meaningless.
The Foreign Ministry also voiced support for Iraqi Prime Minister Nuri al-Maliki in cracking down on "illegal" Shia militias, a few days after an Iraqi delegation visited Tehran to urge it to stop backing such armed groups.
Washington accuses Shia Iran of funding, arming and training Iraqi militias to attack US and Iraqi government forces, despite its public commitment to stabilising Iraq. Tehran blames the violence on the US presence in Iraq.
The US and Iran have held three rounds of talks in Baghdad since May last year on ways of reducing violence in Iraq, but a planned fourth meeting has been postponed repeatedly.
"Right now, what we observe in Iraq is a massacre of the Iraqi nation by the occupying forces," Foreign Ministry spokesman Mohammad Ali Hosseini told a news conference. "Concerning this situation, talks with America will have no results and will be meaningless."
A unnamed Iranian official was last week quoted as saying Tehran saw no need for more talks with the United States on Iraq until what he described as US attacks on Iraqis stopped, but Mr Hosseini's comments were the first such remarks made publicly.
"Tehran has repeatedly used its capacity to strengthen stability in Iraq among various groups," Hosseini added.
Ties between Iran and Iraq have improved since Sunni Arab Saddam Hussein was ousted in the US-led invasion and a Shia-led government came to power in Baghdad.
Analysts say Tehran wants to keep a friendly government in charge but also wants to ensure rival Iraqi Shia factions look to Iran as a power broker.