MOSCOW - Three refurbished Russian attack helicopters have been removed from the Alaed, a transport ship that was delivering them to Syria, the Russian news agency Interfax reported Friday.

Interfax quoted an unnamed source saying that the trio of Mi-25 helicopters had been offloaded at the port of Baltiisk, in the Russian enclave of Kaliningrad on the Baltic Sea.

"Three helicopters were unloaded from the Alaed during a brief stay at Baltiisk. The helicopters are likely to be moved to the 150th Aircraft Repair Plant in the town of Lyublino-Novoye outside Kaliningrad, where they will be kept, pending other decisions," the source told Interfax.

The Interfax report did not say when the helicopters had been removed from the ship. Earlier reports indicated that the Alaed had departed Baltiisk on July 18, sailing in a northwestern direction.

The ship's owner told Interfax that the ship would sail to St Petersburg, where it would take on additional cargo, and then continue on to the Far East.

Last week Russia said it would freeze arms sales and deliveries to Syria while the conflict there escalates.

The move comes after strong international criticism of Russia's continued arms relationship with Syria. Syrian opposition groups have accused the government of using helicopters to attack rebel and civilian targets.

Last month Secretary of State Hillary Clinton publicly criticized Russia's decision to return the Soviet-era helicopters, which had been sent back to Russia for repairs.

Russia is Syria's largest arms dealer, accounting for billions of dollars in sales in recent years.

On Thursday the U.S. House of Representatives passed a bill that would require the Pentagon to end a $171 million contract with Russia's arms export monopoly, Rosoboronexport, because of Moscow's continued arms trade with Syria. The contract was to purchase helicopters for the Afghan army.

Sponsors of the bill said that Russia sold Syria $1 billion worth of arms last year, including explosives, sniper rifles, ammunition and other weapons that could be used in the conflict. Russia has insisted the arms it sells to Syria, such as air defense missile systems, could not be used against civilians.

Russia has so far rebuffed Western pleas to sever ties with Syrian President Bashar al-Assad, a longtime ally. On Thursday Russia and China vetoed a United Nations Security Council resolution that would have extended the U.N.'s observer mission in Syria, but also threaten additional sanctions on the Assad government.

On Friday, Russian officials said they would support a Pakistani draft resolution that would extend the observer mission by 45 days. The mission's mandate expires today.