Zalmay Khalilzad, who served as US ambassador to Afghanistan, Iraq and the United Nations under president George W Bush, is being investigated by American authorities for suspected money laundering, Austrian officials said.
State prosecutor Thomas Vecsey confirmed a report in the Austrian weekly Profil about the investigation of Khalilzad, who played a key role in the political transition in Afghanistan after the 2001 US-led invasion and the fall of the Taliban.
According to the magazine, the investigation centres on the alleged transfer of 1.15 million euro (£920,000) in May 2013 to an account in Vienna owned by Khalilzad's wife, Cheryl Benard. The money came from business activities in Iraq and the United Arab Emirates, it reported. Mr Vecsey would not elaborate on the allegations, nor did the magazine's report.
Profil said the case became public after a blogger found documents while rummaging through a rubbish container used by the state prosecutor's office in Vienna.
The magazine said several bank accounts owned by Benard were ordered frozen in February - a ruling that is under appeal. Benard's lawyer, Holger Bielesz, told Profil that US authorities have yet to express "reasonable grounds for suspicions".
Khalilzad was born in Afghanistan and went to the United States as an exchange student. He later became a professor and a favourite of Republican presidents, especially Mr Bush.
Khalilzad was the US special presidential envoy to Afghanistan from 2001 to 2003, then US ambassador there until 2005. He was the ambassador to Iraq from 2005 to 2007, and the US permanent representative to the United Nations from 2007 to 2009.
Many Afghan officials and foreign observers saw Khalilzad as the country's de facto ruler in the initial months after the Taliban's collapse. He took centre stage organising the traditional grand councils, or loya jirgas, that would eventually approve Afghanistan's constitution.
In the private sector, Khalilzad is founder and president of Gryphon Partners, which advises companies and wealthy individuals on business opportunities in several industries and regions, including high-risk territories.
He sits on the boards of the National Endowment for Democracy, America Abroad Media, the Middle East studies centre at Rand Corp, the American University of Iraq and the American University of Afghanistan. He also has a role at the Centre for Strategic and International Studies, and writes about foreign policy issues and frequently appears on US news shows.
Khalilzad holds bachelor's and master's degrees from the American University of Beirut, as well as a doctorate from the University of Chicago.