Conservative opposition National Action Party, or PAN, chairman Gustavo Madero said he had no ties to Oceanografia, a firm under investigation by Mexican authorities for allegedly defrauding Banamex of hundreds of millions of dollars, and called on officials to get to the bottom of the case.

"I am sure that the officials who ran Pemex in the past 12 years, as well as the members of its board during that time, can provide the detailed information on the Oceanografia case," Madero said in a statement.

Oceanografia, a contractor for state-owned oil giant Petroleos Mexicanos, or Pemex, is owned by businessman Amado Yañez.

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

Oceanografia was seized last Friday on an order issued by the Attorney General's Office and a receiver was named to run the company.

Investigators should go after "whoever is responsible regardless of the consequences" and irrespective of party affiliation, Madero, who is seeking re-election as the PAN's chairman, said.

The PAN governed Mexico from 2000 hasta el 2012.

The politician denied having any ties to Oceanografia in the wake of the publication of a photograph showing him using a plane belonging to the company, which provided oil well repair and maintenance services to Pemex.

"I do not know its owners and I have never had any dealings with any of its officials or operators," Madero said, adding that the air travel was arranged by Congressman Jorge Rosiñol Abreu.

"I did not participate nor did I have any involvement in this situation," the PAN chairman said.

Prosecutors are investigating possible money laundering by the company and its executives.

Oceanografia has been the subject of about 30 lawsuits in U.S. federal courts since 2001, the Reforma newspaper reported.

A Minnesota company sued Oceanografia for not repaying a $9.5 million loan made in 2006 for the purchase of an executive jet and is the subject of two other lawsuits for failing to make the lease payments on two boats, Reforma said.

U.S. officials have asked Citigroup to provide information about the operations of its Mexican banking unit, with the requests coming days after the New York-based fianancial services company cut its 4th-quarter and full-year 2013 earnings due to the fraud detected at Banamex. EFE