Updated

President Vladimir Putin on Wednesday ordered Russia's special services to hunt down the killers of four Russian hostages in Iraq, the Kremlin said.

"The president has ordered the special forces to take all necessary measures to find and destroy the criminals who killed Russian diplomats in Iraq," the Kremlin press service said.

It did not specify what forces might be involved. Agents of the Foreign Intelligence Service and the Federal Security Service — the main successor to the KGB — could be considered special forces.

CountryWatch: Russia

Putin also said Russia "will be grateful to all its friends for any information on the criminals," the Kremlin said.

The order follows Monday's confirmation by the Foreign Ministry that four Russian Embassy workers seized in Iraq in early June had been killed.

Earlier Wednesday, the lower house of the Russian parliament decried the murders and said that "occupying" countries are losing control in Iraq.

Russia has strongly opposed the U.S.-led military campaign in Iraq.

The statement by the State Duma "deplores the death of our compatriots ... expresses profound indignation over the fact of their brutal murder and strongly denounces the criminals, who committed that heinous crime."

It said the abduction and killing were possible because "of the deepening crisis in Iraq, while the occupying countries are losing control over the situation, and terror and violence are becoming the order of the day in that country."