BAGHDAD, July 26 (Reuters) - Militia crews firing mortars and rockets have been hitting Baghdad's heavily protected Green Zone with more accuracy in the past three months because of training from Iran, a top U.S. general said on Thursday.

"In the last three months we have seen a significant improvement in the capability of mortarmen and rocketeers to provide accurate fire into the Green Zone and other places," Lieutenant-General Raymond Odierno told a news conference.

"We think this is directly related to training conducted inside Iran," said Odierno, who is the operational commander of U.S. forces in Iraq.

The U.S. ambassador to Iraq accused Tehran of increasing support for militias when he met his Iranian counterpart for a second round of talks on Iraq's violence on Tuesday. Iran rejects the allegations.

The prize targets in the sprawling zone are the U.S. embassy and Iraqi government buildings. Many attacks come from the direction of areas that have a strong presence of Mehdi Army militiamen loyal to anti-American cleric Moqtada al Sadr.

The United Nations, in a recent report in which it complained about the mounting risks of operating in the Green Zone, said attacks were almost daily and 26 people had been killed by indirect fire between mid-February and late May.

On July 10, militants launched one of the biggest mortar and rocket barrages on the zone, killing at least three people, including a U.S. military service member, and wounding 18.

Washington has accused Shi'ite Muslim Iran of fomenting violence in Iraq by providing weapons training and funding to Shi'ite militias fighting U.S. and Iraqi security forces. They are particularly concerned about sophisticated roadside bombs known as explosively formed penetrators that can destroy a tank.

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