The first group of soldiers went on duty in Italian cities Monday as part of a controversial government scheme to deploy 3,000 troops to help police fight crimes.

Under the plan coordinated by the Ministry of Interior and Defense, 2,000 troops will guard "sensitive sites" such as embassies and government buildings, while another 1,000 will join police on mixed street patrols of large cities.

Italian soldiers guard a metro train station with a police officer (L) in suburban Rome August 4, 2008. [Xinhua/Reuters Photo]

"This isn't a magic wand, but without a doubt it's an important measure for which all Italians, and especially those living in the cities involved, should be grateful," Interior Undersecretary Alfredo Mantovano said while launching the first mixed patrols in the southern city of Bari.

Defense Minister Ignazio la Russa echoed Mantovano as he watched troops assume duty in Milan, saying the scheme was "a step in the right direction."

"There is a stronger perception of safety, an important element which responds to the needs expressed by citizens," he said.

The scheme has been slammed by the center-left opposition, which says it is a stunt to meet an alleged crime and immigration emergency that is not borne out by statistics.

They also predict it will scare away tourists while doing little to deter criminals.

Italian soldiers check the documents of sidewalk vendors outside a metro rail station in suburban Rome August 4, 2008. [Xinhua/Reuters Photo]

But La Russa defended the plan, reiterating that only "vandals, rapists and those who commit theft and robbery" should fear the presence of the soldiers.

"These men (soldiers) have no intention of striking terror in any normal citizen - only the criminals," he said.

The troops will be deployed for six months, but the government has said it may extend the scheme for a further six months if it proves successful.

Troops from the army, navy, air force and paramilitary police are being deployed under the scheme.