Iraq's prime minister has canceled a recently signed arms deal with Russia after "suspicions over corruption" surfaced, his spokesman said.

Under the $4.2 billion deal forged last month, Russia would deliver attack helicopters and mobile air-defense systems to Iraq.

Ali al-Moussawi, an adviser to Iraq's Prime Minister Nuri al-Maliki, said the prime minister has ordered an investigation into the deal after he came home from a trip to Russia with concerns over "corruption"

Al-Moussawi didn't provide details or context about any shady activity. Despite al-Maliki's move, he said, Baghdad wants to salvage an agreement with Russia.

"We informed Russia about our decision, but we hope to sign a new weapons deal between Iraq and Russia. However, talks are still ongoing" al-Moussawi said.

A source in Russia's arms export industry said "supposed corruption claims have never been and cannot be the basis for annulling contracts, particularly in the military-technical cooperation sphere," Russia's state-run RIA Novosti reported.

"At the very least, we must await clarification from official Iraqi bodies where they lay out their intentions," he said.

Observers have said the deal was a sign that Iraq is starting to look beyond Washington for weapons.

But Middle East analyst Ramzy Mardini, an adjunct fellow at the Beirut-based Iraq Institute for Strategic Studies, said he "highly doubts" that suspicions of corruption motivated al-Maliki's cancellation of the deal.

He said he believes al-Maliki's decision could be a "smokescreen" hiding his political calculations.

Mardini said "going to Russia may simply be a way for Iraq to decrease its vulnerability and dependency on the United States." He said he thinks al-Maliki could be playing Moscow and Washington off one another to "increase flexibility of action and decrease dependency on any single actor."

"If Washington is playing rough with him and threatening to cut off military aide due to Iraq's foreign policy in Syria, then flirting with Moscow is his way of getting the U.S. to play ball. Conversely, he could be simply pressuring the Russians to put forth a better deal," Mardini said.

The United States led a coalition to Iraq to topple Saddam Hussein's regime in 2003 and has helped the Iraqi government maintain stability during the Iraq War. U.S. troops departed Iraq at the end of 2011, but Washington still maintains close relations with Baghdad.

Asked whether the United States twisted Iraq's arm to suspend the contract, al-Moussawi said "there was absolutely no pressure by any side, Iraq's sovereignty must be respected."

The U.S. Embassy in Baghdad has stressed that the United States also has billions of dollars worth of military equipment deals with Iraq.

"We would note that the government of Iraq has consistently indicated a strong preference for the United States as its partner of choice for arms purposes," a U.S. Embassy spokesperson recently told CNN.

Iraq has initiated 467 foreign military sales with the United States worth more than $12.3 billion, the U.S. Embassy has said. Some Iraqi officials have complained that weapons deals with the United States are progressing slowly.

"We fully support efforts to purchase equipment to meet its legitimate defense needs and we are committed to working with them to fulfill these military equipment orders as quickly as possible," the embassy said.

Russia recently lost another arms deal tender to supply the Mi-28EN to India, which was won by America's Boeing AH-64 Apache, RIA-Novosti reported.

Mardini said rumors circulated in Baghdad last summer over unilateral cuts in the U.S. foreign military sales program, and that "raised a lot of eyebrows in the prime minister's inner circle."