* Owners of Banco Penta charged with tax evasion, bribery

* Politicians also being probed

* Case is latest in wave of political and financial scandals

SANTIAGO, March 4 (Reuters) - Charges of bribery and tax evasion were formally pressed against the owners of a Chilean financial company on Wednesday, in a probe that has sucked in business leaders and politicians and angered Chileans.

Investigators formalized the allegations against Carlos Delano and Carlos Lavin, owners of Banco Penta, which has insurance operations and controls private health group Banmedica .

The prosecutors have asked the judge to hold Delano and Lavin in custody pending trial.

A probe into fake receipts allegedly used by the Penta owners to dodge taxes has widened. Prosecutors say they now have evidence that such receipts were also used to make illegal campaign finance contributions, principally to the right-wing UDI party.

The scandal has caused waves in Chile, which is proud of its reputation as a relatively corruption-free part of Latin America but has been buffeted by a number of cases over the last year that have weakened trust in the business and political elite.

Thursday's hearing was covered live throughout the day by local broadcasters, with protesters outside the courts shouting abuse at the accused as they emerged.

Prosecutor Carlos Gajardo said that Penta had become "a machine to defraud tax authorities".

But Lavin said the prosecutors' request for pre-trial detention was "inappropriate".

"I am no mafioso," he said to reporters outside the court.

The prosecutors said they were also looking at pressing charges against eight others for bribery and money laundering, including Pablo Wagner, who was a junior mining minister during the last right-wing administration.

The case has weighed on the popularity of the UDI, already tainted in many Chileans' eyes by its links to the 1973-1990 dictatorship of Augusto Pinochet.

Last year, Pinochet's former son-in-law Julio Ponce, chairman of massive nitrates firm SQM, was fined by regulators for his role in an illicit trading ring, alongside other executives and brokers.

But the center-left government of Michelle Bachelet has not been left untouched by scandal. Last month, her son resigned from his position as head of her charitable foundation after accusations that he and his wife used political connections to get privileged access to a bank loan.

The judge in the Penta case will decide by the end of the week whether to hold Lavin and Delano in custody, once the defense has set out its case.

(Reporting by Antonio de la Jara and Rosalba O'Brien; Editing by David Gregorio)