A Miami-based businessman pleaded guilty on Thursday to conspiring to pay $4.4 million in bribes to officials at a state-controlled oil company in Ecuador.

Armengol Alfonso Cevallos Diaz pleaded guilty in the U.S. District Court for the Southern District of Florida to one count of conspiracy to violate the Foreign Corrupt Practices Act and one count of conspiracy to commit money laundering, the U.S. Justice Department said.

At a plea hearing Thursday, Mr. Cevallos admitted to soliciting and funneling bribes from an oil services company to officials at Petroecuador, according to the Justice Department. His sentencing is scheduled for April, prosecutors said.

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Ana Davide, a lawyer for Mr. Cevallos, a citizen of Ecuador who lives in Miami, said her client accepted responsibility for his actions. But she took aim at the FCPA, the law used to prosecute Mr. Cevallos.

“We should not be taking people that aren’t American citizens and prosecuting them in the U.S. for actions that took place in another country,” Ms. Davide said.

Mr. Cevallos’s guilty plea is the latest in an expanding corruption investigation focused on bribes paid to Petroecuador. Prosecutors have so far announced charges or guilty pleas involving 13 individuals, according to a Justice Department spokesman.

In at least one of the cases, Petroecuador petitioned the U.S. court for financial restitution, claiming it was a victim of the bribery scheme.

A magistrate judge in Miami in September denied Petroecuador’s request, saying a pervasive level of illegal conduct among the state-controlled company’s principals precluded it from being recognized as a victim under U.S. law.

Write to Dylan Tokar at dylan.tokar@wsj.com