Authorities have foiled Iraqi plans to bomb a luxury hotel in Amman and poison water used by Jordanian and U.S. troops, sources familiar with the investigation said Tuesday.

Four Iraqis were arrested last week in the plot against Amman's Grand Hyatt hotel, which is frequented by Americans and other Westerners, including about 70 journalists, the sources said, speaking on condition of anonymity. Hyatt officials said they were unaware of a terror plot.

Jordanian Information Minister Mohammad Affash Adwan indicated there had been Iraqi attempts to undermine Jordan's security.

"This is purely a security matter, which is being investigated, and I can't discuss it further," Adwan told The Associated Press.

Iraqi Embassy spokesman Jawad al-Ali declined to comment to the AP, but told Paris-based Radio Monte Carlo the allegations were "completely untrue."

The alleged water-contamination plot involved five Iraqi diplomats kicked out of Jordan on March 23, the sources said.

They said the water is pumped from Zarqa, 17 miles northeast of Amman. Zarqa water plants supply distant villages in Jordan's eastern desert, where there are several army and air bases, including one near the Iraqi border where hundreds of U.S. soldiers are manning anti-missile batteries.

When it expelled the five Iraqi diplomats, Jordan said they had carried out actions "incompatible" with their diplomatic duties. The government later said two could stay, but the Iraqi Embassy said all five had already left the country.

Jordanian Foreign Minister Marwan Muasher said the expulsions were ordered on security grounds. He and other government officials declined to elaborate, saying it was inappropriate during the war in Iraq.

Aware of strong anti-war sentiments among Jordanians, the government has been trying to distance itself from the conflict in Iraq, which supplies all its oil needs at cheap prices.

One day after the deportations, Jordanian authorities also detained four Iraqi transport officials for questioning. No details emerged, but officials said those four -- two employees with Iraqi Airways and two with a joint Jordanian-Iraqi transport company -- had been released.

Four others arrested in connection with the hotel plot remain in custody. The sources declined to say when those arrests were made.