By Crispian Balmer

ROME (Reuters) - Italy is likely to start easing its coronavirus lockdown from May 4 though the long-awaited rollback will be cautious and calculated, Prime Minister Giuseppe Conte said on Tuesday.

The country has been one of the hardest hit in the world by the COVID-19 pandemic, with more than 24,100 people killed since the contagion first emerged in February.

Looking to contain the spread, the government introduced sweeping curbs in March, telling Italians to stay at home and shutting schools, businesses and industries nationwide.

The restrictions have put a major strain on the euro zone's third largest economy but with the number of new cases gradually slowing, Conte said he would unveil by the weekend government plans to loosen the shutdown.

"I wish I could say: let's reopen everything. Immediately. We start tomorrow morning...But such a decision would be irresponsible," Conte wrote in a Facebook post.

He promised "a serious, scientific plan" that would include a "rethinking of modes of transport" to enable workers to travel in safety, new business rules and measures to check whether the loosening was leading to an uptick in infections.

"It is reasonable to expect that we will apply it from May 4," he said, adding that a rushed, disorganised exit strategy would make a mockery of the sacrifices Italians had accepted.

But Conte did not give any specific details about which businesses would be allowed to reopen first or what limits might be maintained on movement around the country.

Countries around the world are considering or taking steps to ease lockdowns, though the World Health Organization is warning this should be done slowly and only when there is capacity to isolate cases and trace contacts.

PRESSURE FOR EASING

Italian business leaders have been clamouring for a relaxation of restrictions, which are among the toughest in the world, warning of economic catastrophe if the lockdown drags on.

Italy's Treasury expects the economy to contract by around 8% this year, which would be the country's worst recession since World War Two, two sources close to the matter told Reuters on Monday.

Speaking to parliament on Tuesday, Conte promised additional measures by the end of the month, worth at least 50 billion euros ($54.3 billion), to mitigate the impact. This will be added to a 25-billion-euro package approved last month.

The prime minister said national efforts to contain the crisis would have to be backed up by initiatives at a European level - a barbed issue that has severely dented Rome's once rosy relations with the European Union.

Italy says the time has come for countries that share the euro currency to issue joint bonds to help share the cost of rebuilding Europe's economies. While southern states have backed the call, wealthy northern nations have rejected the idea.

Conte told the Senate that the future of the EU depended on it finding sufficient common resources to tackle the crisis, but acknowledged that a deal would not be found when European leaders held talks via a video-conference on Thursday.

"I don't believe the upcoming meeting of the 27 leaders will find a definitive solution, but I will do everything...to ensure it expresses a clear political path in the only reasonable direction," he said.

($1 = 0.9201 euros)

(Reporting by Francesca Piscioneri, Agnieszka Flak, Angelo Amante, Giuseppe Fonte and Gavin Jones; Editing by Mark Heinrich)