The Panamanian authorities have raided the offices of Mossack Fonseca

MEXICO CITY — The Panamanian authorities have raided the offices of Mossack Fonseca, the law firm at the center of the vast leak of documents this month that exposed the global use of offshore tax shelters, and spent at least 16 hours combing through the company’s files looking for evidence of possible “illegal activities,” officials said on Wednesday.

The search at the company’s headquarters in Panama City, which was led by an organized crime unit from the attorney general’s office, began Tuesday afternoon and lasted until Wednesday morning. Other groups of investigators also searched subsidiaries of the firm in Panama and a Panamanian telephone company’s data support center, officials said.

The disclosure of about 11.5 million documents from the firm, which specializes in setting up offshore accounts, laid bare the elaborate system of shell companies that the world’s wealthy and powerful use to stash their money, often in an effort to minimize or avoid tax payments.

The revelations have spurred criminal investigations around the world, brought pressure on senior politicians in numerous countries and led to the resignation of the prime minister of Iceland, Sigmundur David Gunnlaugsson.

The Panamanian investigators were gathering documents related to news articles “that establish the possible use of the law firm in illegal activities,” the Public Ministry of Panama, which includes the attorney general’s office, said in a statement.

Sandra Sotillo, spokeswoman for the Public Ministry, said in a phone interview that investigators were “trying to verify whether the information published in the news media was true.”

Computer forensics experts and financial analysts accompanied prosecutors and police officers on the raid at the company’s headquarters, according to La Prensa, a Panamanian daily.

The search came a day after the Peruvian authorities raided the Lima offices of the law firm and seized accounting documents. Peru’s tax agency issued a statement saying that investigators were exploring whether shell companies established by the firm had been used to commit crimes in Peru.

Prosecutors from the intellectual property division of the attorney general’s office in Panama visited Mossack Fonseca’s offices in Panama City on Monday to explore the firm’s contention that the leak was the work of an outside computer hacker rather than an inside job.

The firm and its co-founders, Ramón Fonseca and Jūrgen Mossack, have asserted that they committed no crimes and that the authorities should be focusing not on their work but on the cause of the leak. They have said that they are not responsible for the actions of the shell companies and the use of the offshore accounts they help create.

“We stand ready, willing and eager to cooperate with the authorities again on their latest investigations to ensure this situation is brought to a just conclusion,” the firm said in a statement on Tuesday as the sweep in Panama City unfolded. “In this case, we’re the ones against whom a crime has been committed. Our systems having been unlawfully breached by parties external to the firm.”

News of the latest raid in Panama City came as tax officials from around the world gathered on Wednesday in Paris under the aegis of the Organization for Economic Cooperation and Development to discuss the worldwide implications of the leak of documents.

President Juan Carlos Varela of Panama has said that his government would form an international committee of experts to review the country’s legal and financial practices and to propose measures that would increase transparency in the global financial sector. His government on Tuesday announced that the economist Joseph Stiglitz would be a member of the panel.