UPDATE 3-Italian Senate chief to attempt interim government

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By Stephen Brown and Gavin Jones

ROME, Jan 30 (Reuters) - Italian Senate speaker Franco Marini agreed on Wednesday to try to form an interim government aimed at reforming electoral rules that are blamed for the collapse last week of the 61st government since World War Two.

But Marini, chosen for the role by the president six days after centre-left Prime Minister Romano Prodi resigned, faces an uphill task convincing opposition leader Silvio Berlusconi and his allies to drop their demands for immediate elections.

"I will concentrate my efforts on trying to do this as quickly as possible," said 74-year-old Marini, who must try to garner cross-party support for an interim government, with himself as prime minister. He admitted his task was "difficult".

Talks start on Thursday afternoon and are unlikely to finish before Monday, a political source told Reuters. Should Marini fail, the president would have to call a snap election, which could be held in April at the earliest.

Currently the second highest-ranking official in Italy after President Giorgio Napolitano, Marini's neutral role as president of the upper house may give him a chance of reaching consensus, although he is from Prodi's centre-left Democratic Party.

But Berlusconi, who has recovered his lead in opinion polls after losing power to Prodi in 2006 and senses the chance for a quick win, said he did not want to "waste time". "We will tell Marini that we want elections right away," he said.

The crisis has left the euro zone's third largest economy without a strong, credible government, just as the global economy is slowing down and Italian business and consumer confidence is at its lowest for at least two years.