Rome - With its first contingent of 800 peacekeeping troops due to reach Lebanon today, Italy is basking in general international praise for its foreign policy that has few precedents since its emergence as a western democracy in the late 1940s.

But at home there are misgivings about whether Italy's centre-left government is overplaying its hand and being less than frank about the full range of motives behind its unusually prominent role in the Lebanon crisis. "We are facing a scenario like that which led up to the outbreak of the first world war," said Daniele Capezzone of the radical Rose in the Fist party, a member of Italy's ruling coalition.

The comment underlines the anxiety about what Italy may be getting itself into. It is sending up to 3,000 troops under the UN flag to Lebanon and will next year replace France as commander of the mission, designed to keep the peace between Israel and Hizbollah guerrillas.

From the US have come support and gratitude not only from George W. Bush, the Republican president, but from Edward Kennedy, the veteran Democratic senator.

Among many of Italy's European partners, friction with France over who should lead the UN mission is outweighed by admiration for the way that Romano Prodi, prime minister, a former European Commission president, has returned Italy to its role as an inspirer of common European policies.

In Brussels, the sometimes embarrassing episodes associated with the European policies of Silvio Berlusconi, his predecessor, are a fading memory.

In the Middle East, Italy is advancing its historically good ties with moderate Arab states, and the better relationship that Mr Berlusconi developed with Israel, to portray itself as a trustworthy partner for both sides. Though Italy has a fraught relationship with Libya, its former north African colony, it differs from France and the UK in having no colonial past in Middle Eastern lands and from Germany in having no trauma over having annihilated Europe's Jews.

The UN mission has clear risks, a point acknowledged by Arturo Parisi, Italy's defence minister. "What's at risk in Lebanon isn't Italy but the capacity of the international community to govern the world, prevent war and promote peace by means of the UN," he said in an interview to be published today by L'Espresso magazine.

Yet Italy's willingness to take the lead in Lebanon is driven by other factors as well. Italy aims to ease tensions with the US over its imminent troop withdrawal from Iraq by helping out in another regional hot spot central to US interests.

Italy also wants to block Germany's demand for a permanent UN Security Council seat, a campaign that looks more convincing if Italy, unlike Germany, takes centre stage in such a dangerous UN military operation.

With France and the UK already having permanent council seats, Italy has long feared German membership would consign it indefinitely to the second rank of European powers.