UPDATE 3-Italy's Renzi expects government in place by Monday
* PM-designate completes talks with political parties
* Expects to name ministers by weekend
* Berlusconi says in opposition but may support individual measures
ROME, Feb 19 (Reuters) - Italian Prime Minister-designate Matteo Renzi said he expected his new government to be in place in time for a formal vote of confidence in parliament on Monday, after he wrapped up consultations with the main political parties.
"I'm convinced that the conditions are in place to do good work," Renzi told reporters on Wednesday after completing talks with parliamentary groups.
He said he expected to give President Giorgio Napolitano his formal acceptance of the mandate to form a government on Saturday, when he is likely to present his cabinet.
Renzi, who met Bank of Italy governor Ignazio Visco after his meetings with the parties, said he planned to spend Thursday working on a policy document and would continue to work on naming his future ministers.
However, he declined to answer questions about the possible identity of his cabinet following media speculation that he was having trouble filling key posts including the vital economy ministry portfolio.
The economy minister will play a vital role as a contact point for Italy's European partners and a source close to Renzi said aides were in contact with both Napolitano's office and the European Central Bank.
A spokesman for the central bank in Frankfurt said, however, that it was not the ECB's job to take part in the formation of a government.
Italian media have speculated on a wide range of possible candidates but there was no word on whether he would pick a politician with experience in running a large administration or a technocrat similar to the outgoing incumbent, former Bank of Italy official Fabrizio Saccomanni.
"We need a high-profile figure. Whether it's a politician is not the main issue," the source said.
Renzi has promised a radical policy programme with reforms to the electoral and constitutional system, to the labour market, and to the public administration and tax systems within the first four months of taking office.
However, details have been sketchy, and there has been particular attention on his likely attitude to EU budget rules, following several public statements suggesting he would like to breach strict deficit limits to gain more room for his reform agenda and investment in infrastructure.
Renzi was given a mandate to form a government after his centre-left Democratic Party forced his rival Enrico Letta to resign as prime minister last week following heavy criticism over the slow pace of economic reform. After years of tight austerity policies aimed at controlling a 2 trillion euro public debt, Italy's stagnant economy is barely growing, with unemployment, particularly among young people, at record levels.
Renzi is expected to form a coalition based around his own centre-left Democratic Party and the small centre-right NCD party, which supported Letta, but he has also met parties expected to be in the opposition.
On Wednesday he met both former Prime Minister Silvio Berlusconi, with whom he has already reached an agreement on reforms to the electoral and constitutional system, and Beppe Grillo, leader of the anti-establishment 5-Star Movement.
Both will go into opposition, but the reaction from the two leaders was starkly different, with Berlusconi emerging from the meeting in conciliatory mood.
"We will be in opposition, but we will support individual measures if we consider they are good for the country," Berlusconi, with whom Renzi has already reached an accord on electoral law reform, told reporters.
By contrast Grillo delivered a blistering attack on the would-be prime minister during a 10-minute meeting that was broadcast live.
"You're not a credible person. Whatever you say isn't credible," Grillo told the 39-year-old Renzi, who struggled to get a word in. "You say a thing one day and then go back on it the next day. You're a young boy, but at the same time you're old," he said.