ROME -- Italy's president asked political neophyte Giuseppe Conte to try to form a government Wednesday, giving the euroskeptic 5-Star Movement and anti-immigrant League a shot at running western Europe's first populist government.

Conte, a law professor who never has held political office, met with President Sergio Mattarella for nearly two hours amid concern in Brussels and markets made skittish by the possibility of Europe's third-largest economy taking an isolationist turn.

Conte, 53, immediately sought to reassure international allies, confirming Italy's place and commitments in Europe and acknowledging the "delicate and difficult phase" the European Union was entering with budget negotiations looming.

But the premier-designate also stressed that his first priorities were Italians themselves, and that he was committed to implementing a government program agreed to by the 5-Star and League leadership that calls for budget-busting measures and an immigration crackdown.

"I will be the defence lawyer of the Italian people," he said in brief remarks at the presidential palace before departing in a taxi.

With a mandate in hand, Conte must now huddle with the 5-Stars and League to finalize a list of Cabinet ministers to present to Mattarella. Once the Conte-headed government is sworn in, its policy agenda would be put to confidence votes in both houses of parliament, where the two blocs have a slight majority.

The anti-establishment 5-Stars and anti-immigrant League proposed Conte as their compromise candidate for premier Monday after inconclusive March 4 national elections led to a hung parliament and more than two months of political deadlock.

Questions immediately swirled over Conte's qualifications. His legal expertise is in civil and commercial law, and his published resume suggests he padded his bonafides with academic credentials at elite international universities where he never taught or enrolled.

Financial markets have reacted nervously to the 5-Star-League program, which includes a budget-busting basic income for needy Italians and a two-tier flat tax that is expected to add to Italy's debt load, already Europe's heaviest after Greece.

European Commission Vice-President Valdis Dombrovskis warned Italy on Wednesday to rein its government debt, which is currently over 130 per cent of gross domestic product. The 19 members of the euro currency should keep public debt under 60 per cent of GDP and their budget deficits below 3 per cent of GDP.

Both 5-Star leader Luigi Di Maio and League leader Matteo Salvini have stood by Conte and sought to reassure markets and EU officials in Brussels. However, they have also noted that Italians voted in large numbers for a tougher approach to the EU in terms of budget negotiations, deporting migrants and improving dialogue with Russia.

Even if a Conte-led government can win the confidence votes in parliament, analysts predicted a ruling coalition of such uneasy bedfellows would not last the full five-year term and that another parliamentary election in 2019 remains a possibility.

Outstanding questions for the near-term include Conte's list of proposed Cabinet ministers. The anti-euro tendencies the League-favoured candidate for economy minister, Paolo Savona, has expressed in the past have worried Brussels.

Political observers in Italy say a bigger, more immediate issue for Conte is persuading Mattarella he would have the independence to lead a coalition government composed of the 5-Stars and the League, and not just be an executor of the populists' wishes.

The 5-Stars have suffered from the perception that their public officials are mere puppets of the movement's brain trust. Six months after Rome Mayor Virginia Raggi's 2016 election, 5-Star founder and comic Beppe Grillo stepped in to personally shake up her administration after it became mired in scandal, criminal investigations and resignations.