Rome - Italy's economy has "run aground" and must improve its productivity to reverse the relative decline of Europe's fourth biggest economy, Mario Draghi, the new governor of the country's central bank, warned at the weekend.

Speaking only five weeks ahead of a general election likely to be a bitter and close-fought contest, Mr Draghi spelt out the seriousness of Italy's problems, saying: "Gross domestic product did not grow [last year], our products lost even more world market share and the budget deficit increased."

He said: "Since the 1990s, it is as if the economy has run aground." The deficit in growth reflected "the difficulty that producers have in competing. At its roots is the lack of progress in productivity."

His remarks in a speech in Cagliari on Saturday, his most important public appearance since his appointment last December, came as opinion polls showed the centre-right government of Silvio Berlusconi, prime minister, trailing a broad centre-left coalition led by Romano Prodi. According to an Abacus-Sky TG24 opinion poll last Thursday, the opposition holds a 51.5-47 per cent lead over the government, the same advantage that it had a week earlier.

This would be enough to give the centre-left a majority in both houses of parliament.

The election campaign has blended savage polemical exchanges among politicians with bizarre incidents such as the resignation of Roberto Calderoli, a government minister, after anti-Italian riots erupted in Libya because he wore a T-shirt sporting cartoons of the Prophet Mohammed.

But prominent businessmen have expressed frustration that the campaign, entertaining though it may be in certain respects, has not properly addressed Italy's deep-rooted economic problems.

Luca Cordero di Montezemolo, the head of Confindustria, the employers' association, said last week: "This is the longest and ugliest election campaign since the second world war."

In his speech in Cagliari on Saturday, Mr Draghi reminded Italians that in contrast to the 1990s, when Italy devalued the lira, its former currency, in order to regain competitiveness, that option was no longer available now that the nation was a eurozone member.

"The illusory remedy of competitive devaluations is gone. Productivity growth is the only way to create prosperity," the bank governor said.

Last month Italy reported a trade deficit for 2005 of €10.4bn ($12.4bn, £7bn), its worst performance since the 1980s.

Much of the deficit was attributable to higher energy costs, but another causewas rising unit labourcosts, which reduced the competitiveness of Italian exports.

The economy is also hobbled by a gigantic public debt, which rose last year for the first time since 1994. After statistical revisions due to be published later this month by the Bank of Italy, the debt will be estimated at about 106 per cent of GDP.

"The structural lags of the Italian economy are not signs of an inevitable decline," Mr Draghi said. "They are manifestations of profound, serious problems, which can be tackled."