Panama's government is creating an international committee of experts to recommend ways to boost transparency in the Central American country's offshore financial industry.
President Juan Carlos Varela is trying to shore up confidence in his nation's financial sector after the leaking of 11.5 million documents from a prominent Panama-based law firm which helped create shell companies for the world's rich and famous.
The Panamanian leader said the committee's findings will be shared with other nations so joint action can be taken to boost transparency in legal and financial centres worldwide.
As he takes steps to strengthen controls, Mr Varela defended Panama against what he called a "media attack" by wealthy nations which he says are ignoring their own deficiencies and unfairly stigmatising his country.
Meanwhile, Mexican tax authorities say they are investigating 33 citizens whose names are mentioned in the so-called Panama Papers.
Tax authority head Aristoteles Nunez told Radio Formula some of those mentioned in the documents were already subjects of investigations.
Mr Nunez says authorities are looking at whether the income that contributed to any offshore account was reported in tax returns. If the income was not reported, the owners could avoid fines by reporting the assets and returning the money to Mexico, as long as it is legal in origin.
Prosecutors in El Salvador also are investigating citizens mentioned in the leak. Chief prosecutor Douglas Melendez did not identify any of the Salvadorans involved, and stressed that offshore accounts are not necessarily illegal.
Brazil's UOL news portal reported that an offshore company created by Roberto Carlos, one of the country's most popular singers, appears in the files of Mossack Fonseca, the Panamanian law firm at the centre of the matter.
Blogger Fernando Rodrigues said on UOL that Carlos is one of the shareholders of Happy Song, an offshore company created in 2011 to manage his career.
Carlos' press office told UOL that the company is duly registered with Brazilian tax authorities and the country's Central Bank.
European football governing body Uefa has been raided by Swiss police and has handed over evidence of a Champions League television rights contract with an offshore marketing agency implicated in the Fifa bribery scandal.
The Swiss attorney general's office said it requested raids on the soccer body and "another enterprise" for suspected criminal mismanagement and misappropriation linked to dealings with Cross Trading, an offshore registered agency.
Cross Trading is owned by two men indicted last year by US federal prosecutors who are working with Swiss counterparts to investigate suspected corruption in international football.
Uefa and its Champions League marketing agency - TEAM Marketing, based in Lucerne, Switzerland - had made a 111,000 dollar (€97,000) deal with Cross Trading in 2006 for three seasons of broadcasting in Ecuador.
The 2006 contract - co-signed by current president of world football governing body Fifa, Gianni Infantino, while he was Uefa's legal director - was also leaked from the database of Mossack Fonseca.
Uefa acknowledged that Swiss federal police "acting under a warrant" came to see its contracts with Cross Trading.