The disclosures contained in a massive leak of documents from a Panamanian law firm reverberated worldwide on Monday.
In Pakistan, Prime Minister Nawaz Sharif's government defended his children's ownership of offshore companies.
The embattled premier was one of several world leaders named in the so-called Panama Papers, a trove of files that belonged to the secretive Mossack Fonseca law firm, whose contents shed light on how the wealthy and powerful stash their money in offshore tax havens.
An anonymous source first leaked the documents to the Sueddeutsche Zeitung newspaper, based in Munich, Germany, last year, which shared them with several international media outlets. Many of those outlets published reports on the documents Sunday, in collaboration with the International Consortium of Investigative Journalists.
Those reports allege that three of Sharif's children maintained offshore companies in the British Virgin Islands, through which they owned half a dozen properties overlooking London's tony Hyde Park. Sharif himself was not named as an owner of any of the companies or properties.
While analysts said that maintaining offshore bank accounts may be legal under Pakistani laws, the practice could expose the country's wealthy political elite to fresh allegations of corruption and money laundering in a country in which more than half the people live on less than $2 a day.
Opposition leader Imran Khan accused Sharif of acquiring the properties and transferring them to his children to shield himself from liability under Pakistani tax laws. Khan said that Pakistan's National Accountability Bureau, an anti-corruption watchdog, "must take action" to determine how Sharif's family obtained the money to set up the offshore accounts.
"Our stance vindicated again as Sharif's wealth stashed abroad exposed," Khan tweeted.
Hussain Nawaz Sharif, the prime minister's eldest son, said he owned the offshore companies named in the leaks but that he and his family members had broken no laws.
"I have been living abroad for many years and have invested there. I have not done anything illegal," Sharif told the Geo TV news channel. "I have been doing business according to Pakistan's foreign act and other Pakistani laws, including the income tax laws."
The Sharif family denied any wrongdoing in a statement on Monday. "None of the corporations mentioned are owned or run by Mr. Nawaz Sharif, the prime minister of Pakistan," the statement said.
"All of the corporations owned by the Sharif family (by Mr. Hussain and Mr. Hassan Nawaz) are legal and financially sound. No new information has been disclosed by the Panama leaks and ICIJ which was not already in the public domain," the statement continued. "It is regretful that some elements in media and political rivals are disseminating factually wrong information and distorting it for political purposes."
Maryam Safdar, Sharif's daughter, who is widely seen as his political heir, and his son Hassan Nawaz Sharif were also named as trustees or owners of companies based in the British Virgin Islands, a popular tax haven. According to the Indian Express newspaper, which was given access to the leaked documents several months ago and conducted subsequent investigations, Sharif's children mortgaged four London properties in exchange for a loan of 7 million British pounds, about $10 million at current exchange rates.
Pervaiz Rashid, Pakistan's information minister and a close aide to Sharif, said the premier's children filed tax returns in accordance with Pakistani laws "and do business abroad like children of common Pakistanis do." He also criticized Khan, the opposition leader, whose two sons study at expensive private schools in Britain.
"Imran Khan's allegations are wrong; he should at least express regret," Rashid said.
Sahi is a special correspondent. Staff writer Bengali reported from New Delhi.