ROME (AP) — Police on Tuesday searched the offices and homes of a former Italian premier and several leading business executives in an investigation of alleged corruption involving the sale of military planes, ships and submarines to Colombia, Italian state television reported.

Massimo D’Alema, a leftist politician who served as Italian premier from 1998-2000, is among those reported to be under investigation.

The sales deal, said to be worth 4 billion euros ($4.5 billion), has been under scrutiny for some time. Last year, a top Italian CEO, Alessandro Profumo, told the Senate defense commission that D’Alema had no role in the dealings for the sale on behalf of Leonardo, a major Italian aerospace and defense manufacturer.

Italian state television, citing Naples-based prosecutors, said that Profumo is among prominent business figures under investigation. Profumo's mandate as CEO of Leonardo ended last month.

Neither Profumo nor D'Alema could be reached for comment on Tuesday.

Italian daily Corriere della Sera reported that the investigation looked into initiatives to sell M-346 jets, an advanced military training aircraft manufactured by Leonardo, and corvettes, which are fast naval vessels, and small submarines produced by Fincantieri, a major Italian shipbuilder.

Four Colombians, including a former foreign minister, were among others being investigated, Corriere della Sera said. The former minister who was identified in the Italian news reports as Marta Lucía Ramírez, and who also served as vice president, tweeted that she was “not involved in the purchasing of military equipment.” She said that the Colombian Embassy handled the purchases with the defense ministries of both countries.

Naples prosecutors' offices were closed Tuesday evening, and officials couldn't be immediately reached for comment on the Italian news reports.