Amado Yañez Osuna, the main stockholder in Pemex contractor Oceanografia, was arrested by Mexican prosecutors, officials said Monday.

Oceanografia is under investigation for allegedly defrauding Banamex, a unit of U.S.-based Citigroup, of about $360 million and other irregularities.

Yañez appeared Saturday before prosecutors after they issued a summons against him as part of the investigation, the Attorney General's Office said in a statement.

The businessman "appeared voluntarily before the ministerial authorities" and provided a statement accompanied by his attorneys, the AG's office said.

After Yañez's appearance, prosecutors asked a judge to order his arrest with an eye toward compiling "more evidence ... for probable arrests of those responsible for the fraud" against Banamex, the AG's office said.

Oceanografia was seized on Feb. 28 on an order issued by the AG's office and a receiver was named to run the company.

Officials have said that the fraud does not affect Mexico's banking system, adding that it is very solid with high levels of capitalization and liquidity.

Oceanografia, which operates 87 vessels, provides repair and maintenance services to the Mexican oil well sector. EFE