Prosecutors in Italy are seeking to seize €1.8 billion ($2.4 billion) in assets from Nomura Holdings Inc. as part of an investigation into Banca Monte dei Paschi di Siena SpA's use of derivatives to hide losses.

Sadeq Sayeed, Nomura's former European head, and Raffaele Ricci, a managing director in fixed-income sales, are also being probed for allegedly colluding to obstruct regulators and making false statements, prosecutors in Siena, where the bank is based, said Tuesday.

They are also sequestering €14.4 million in assets from three former Monte Paschi managers already under investigation, including Chairman Giuseppe Mussari, General Manager Antonio Vigni and finance chief Gianluca Baldassarri.