US President-elect Joe Biden's son Hunter has said his tax affairs are under investigation.
The investigation is being conducted by federal prosecutors in Delaware.
Hunter Biden said he took the case "very seriously" but was confident an "objective review" would show he had handled his affairs "legally and appropriately".
The Biden-Harris transition team said the president-elect was "deeply proud of his son".
A statement from the team said Hunter had "fought through difficult challenges, including the vicious personal attacks of recent months, only to emerge stronger".
Hunter Biden said he learned of the investigation on Tuesday. He did not disclose any further details.
The 50-year-old was a frequent target of Republican criticism during the 2020 election campaign, focusing on his business dealings in Ukraine and China when Joe Biden was vice-president in the Barack Obama administration.
Last December, President Donald Trump was impeached by the Democratic-run House of Representatives on charges of abuse of power and obstruction of Congress stemming from his attempts to pressure Ukraine to investigate the Bidens.
But Mr Trump was cleared by the Republican-held Senate in February.
Hunter Biden's Ukraine work 'problematic', says report
The new investigation into Hunter Biden's tax affairs comes as his father assembles his cabinet. If the case is still ongoing when Mr Biden is sworn into office next month, his pick for attorney general could have oversight of the investigation, AP notes.