MILAN, Dec 5 (Reuters) - Milan-based private equity firm Nextalia is preparing to file a joint bid with rival NB Renaissance for Verisem, two sources close to the matter said, after the Rome government stopped China-owned Syngenta from buying the Italian seed producer.

Under former Prime Minister Mario Draghi, Italy in 2021 prevented an acquisition of Verisem by Syngenta, a Swiss-based pesticides and seeds giant owned by China National Chemical Corporation since a $43 billion takeover in 2017.

Under Italian rules, the government has "golden powers" to veto foreign bids for assets deemed of strategic national interest.

The Chinese bid for Verisem, which owns brands such as Suba Seeds and Condor Seed Production, was the first time that Italy exercised such powers in the agricultural sector.

The sources said the two Italian private equity firms were now preparing to file a joint bid for Verisem by a Dec. 20 deadline. Each investment firm will account for 50% of the bid, one of the sources said.

After initially being in competition for Verisem, Nextalia and NB Renaissance decided to join forces to bid for an asset which the sources said was worth between 160 million euros ($173 million) and 180 million including debt.

Nextalia is a venture founded by former Barclays and Mediobanca investment banker Francesco Canzonieri, with backing from top bank Intesa Sanpaolo and insurer UnipolSAI .

Nextalia's private equity arm manages 800 million euros in assets. The firm also runs closed-end funds that buy impaired loans through another 330-million euro business.

NB Renaissance was created in 2015 when Intesa spun off its private equity business, setting up a partnership with U.S. investment firm Neuberger Berman.

NB Renaissance is currently invested in another agricultural business - Sicit, an Italian maker of biostimulants for agriculture.

Earlier this year, NB Renaissance sold bioplastic firm Novamont to Versalis, the chemical company of Italian energy major Eni. In 2022, it sold Italian fertiliser maker Biolchim to U.S. conglomerate JM Huber Corporation.

($1 = 0.9235 euros)