Russia denied Monday that it had sold sensitive military equipment -- including GPS jammers that could throw U.S. bombs and aircraft off course -- to Iraq in violation of U.N. sanction.

Other items reportedly included anti-tank guided missiles and night-vision goggles.

"The Russian Federation is not delivering weapons or weapons systems to Iraq and strictly observes all U.N. Security Council resolutions passed with regard to Iraq," Alexei Volin, deputy head of staff for the government, was quoted as saying by the Interfax news agency.

But the White House on Monday came out and said it has credible evidence Russian companies did sell weapons gear to Baghdad, calling the firms' actions "disturbing." The Bush administration asked Moscow again to halt the sales.

"The United States has credible evidence that Russian companies have provided assistance and prohibited hardware to the Iraqi regime, things such as night vision goggles, GPS jammers and antitank guided missiles," White House spokesman Ari Fleischer told reporters.

"These actions are disturbing and we have made our concerns clear to the Russian government. We've asked the Russian government that any such ongoing assistance cease immediately," Fleischer added.

The Washington Post reported Sunday that three Russian companies were involved in military equipment sales. Fox News confirmed that report. U.N. sanctions have allowed Iraq only to import goods approved by the oil-for-food program.

The State Department said it had raised the issue with senior Russian officials several times, particularly over the past two weeks, because the equipment could pose a direct threat to coalition forces. The United States even provided specific information regarding the transactions to Moscow in hopes the Russians would rein in the dealers.

But Friday was the last straw, as U.S. officials found out the Russian dealers were in Baghdad showing the Iraqis how to use the equipment.

The Russians "sure as hell should have been able to stop these guys," an official told the Post.

The U.S. government suspects that the Russians were hiding some of the jamming equipment in humanitarian aid flights to Baghdad, Fox News has learned. The boxes are about 3 ft. x 3 ft.

Volin called the allegations "not only groundless, but absolutely invented."

Also Monday, Russian President Vladimir Putin called on Iraq to obey international conventions on the humane treatment of prisoners of war after 12 American soldiers were ambushed and believed captured or killed.

Putin told top Cabinet ministers that he had asked the Foreign Ministry "to appeal to Iraq with an urgent request to comply with these particular rules."

The Post identified two of the firms that allegedly sold equipment as KBP Tula and Aviaconversiya, a Moscow-based company. It said KBP supplied antitank guided missiles and Aviaconversiya provided jamming devices.

Aviaconversiya director Oleg Antonov denied the claim, saying on Echo of Moscow radio that, "we have never delivered anything to Iraq."

He said the allegation was "conjecture resulting from the fact that tests of high-precision armaments revealed the total loss of their efficiency against our jamming."

The deputy director of Tula's instrument design office, Leonid Roshal, also denied the report, according to the news agency ITAR-Tass.

A spokesman for Russia's arms export agency, Rosoboronexport, said his organization "100 percent definitely had nothing to do with any sales and we have no information that such sales took place."

Rosoboronexport is the sole state intermediary for Russian military exports and imports.

A spokesman for the U.S. embassy in Moscow said that Moscow's response to the allegations "so far hasn't been satisfactory."

"We hope that the responsible Russian agencies will take our concerns seriously," he said.

Fox News reported in January that Iraq may have obtained as many as 400 electronic "jammers" that could throw America's smart bombs off their programmed path if the U.S. goes to war.

There was "real concern at the highest levels" at the Pentagon that Baghdad may have purchased the jammers from a Russian firm, a senior defense official said then.

If the smart bombs are diverted from their designated targets, they may hit non-military sites and cause civilian casualties -- which could be used to Iraq's advantage.

The types of bombs whose courses may be altered by these jammers are called J-Dams -- for "joint direct attack munitions," guided by global satellites. These are the military's GPS-guided bombs. Each one costs about $21,000 and has a maximum range of 15 miles. J-Dams made their combat debut in Kosovo in 1999.

It's estimated that 80 percent of U.S. weapons that would be used in a war with Iraq would be directed via satellites.

The Air Force is now trying to test similar jammers to see if those used by an enemy can really work on U.S. weapons.

Defense officials confirm the extensive use of GPS-guided munitions, including Tomahawks, JDAMs, and the EGBU-27 used to hit the Iraqi leadership compound on Wednesday night. These are all being used throughout the country. All of the munitions used in Baghdad have been GPS-guided.

Fox News' Teri Schultz and The Associated Press contributed to this report.