Washington, Aug 26 (IANS): The Pentagon said that it was concerned about the arms deal between Iran and Russia for missile systems, a media report said.

"On the S-300, we have long expressed our concerns of reports on this possible sale of this missile system to the Iranians," said Pentagon spokesman Peter Cook on Tuesday.

"We don't see this as a positive development," Xinhua reported quoting Cook.

"At the same time, here at the Defense Department, again, the president will have options available to him even if that system is put into place," said Cook.

According to a media report, Iranian Defence Minister Hossein Dehghan announced on Tuesday an agreement had been reached with Russia for Tehran to procure the S-300 long-range surface-to-air missile systems.

"The text of the contract is ready and our friends will go to Russia next week to sign the contract," Dehghan was cited as saying by Iran's Fars News Agency.

The prospective arms sale came at a time when Iran and six world powers reached a deal in July to limit Tehran's nuclear program in exchange for lifting all nuclear-related sanctions.

The S-300 system, first deployed at the height of the Cold War in 1979, is designed for the air defence of large-scale facilities and can engage ballistic missiles up to 186 miles or about 300 km away.