By Frances Kennedy BBC correspondent in Rome

Mr Berlusconi has been criticised for not visiting the troops sooner

The visit comes at a tense time in Nasiriya, where 13 Italian were hurt in clashes with Iraqi fighters last week.

It also follows the reported abduction of four Italians on the outskirts of Baghdad on Friday.

However, the Italian foreign ministry says it has checked its records and none of its citizens are missing.

Mr Berlusconi, accompanied by the defence chief of staff, told the soldiers Italians were proud of them and the international community also appreciated their work, saying even US President George Bush had phoned him to say so.

Mystery men

The visit took the Italian contingent by surprise.

Mr Berlusconi's opponents have often criticised him for not making a morale-raising trip to the area.

Recently, the prime minister said the troops there were all paid volunteers and they had their work to do.

With the deteriorating situation in Iraq, the government is increasingly sensitive to public opinion, concerned about the conditions and the purpose of the Italian mission.

The visit comes amid mystery surrounding reports that four Italians have been seized by militia on the outskirts of Baghdad.

A Reuters journalist said he saw two burly men being dragged into a mosque, as they were crying, "Italians. We're Italians".

The foreign ministry in Rome says no Italians on their updated list of those present in Iraq are missing.

This has prompted speculation that the men may be private security guards, mercenaries or even spies.