ROME, April 4 (Reuters) - Italy's anti-establishment 5-Star Movement proposed a German-style governing contract with two of its rivals as formal talks aimed at seating a government began on Wednesday, a month after an election ended with a hung parliament. The inconclusive March 4 vote left soft-spoken President Sergio Mattarella to coax sworn adversaries toward a coalition deal. The process could take weeks and still end in deadlock, which would force yet another vote, prolonging instability in the euro zone's third-largest economy. In the election, a center-right alliance taking in the far-right League and four-time prime minister Silvio Berlusconi's Forza Italia won the most seats, followed by the 5-Star and then the PD, but no group can govern alone. Late on Tuesday, 5-Star prime ministerial candidate Luigi Di Maio, who commands the biggest single party in parliament, reached out to both to the center-left Democratic Party (PD) and League leader Matteo Salvini, but with strict conditions. So far, the PD - still influenced by its defeated former chief and ex-prime minister Matteo Renzi - has closed the door to any alliance with 5-Star, and Salvini has refused to break with the center-right bloc. "Salvini has to choose between revolution or restoration. In other words, whether to abandon Berlusconi and start to change Italy, or to cling to Berlusconi and change nothing," Di Maio said late Tuesday on prime-time talk show "Di Martedi". "The PD now must choose whether to follow Renzi's line... which is irresponsible," Di Maio said, opening the door instead to the acting PD chief Maurizio Martina and praising some of the ministers in the caretaker PD government. While Salvini said he would talk to 5-Star, he rejected "vetoes or commands", while Forza Italia's Chamber of Deputies leader Mariastella Gelmini said the center-right should reach out to the PD, not 5-Star. "We won't play these games," the PD's Martina said on Twitter. "Who is seeking to divide the PD won't succeed."