A top PWC executive has left the firm after revelations of PwC links with Isabel Dos Santos, who is under investigation for corruption.PWC declined to comment on the departure and says it has launched its own investigation.Ms Dos Santos, one of Africa's richest women, has said the allegations are a part of a political witch-hunt.The BBC reported how PWC helped Ms Dos Santos with auditing, consultancy and tax advice for her companies.Ms Dos Santos got access to lucrative deals involving land, oil, diamonds and telecoms when her father was president of Angola, a southern African country rich in natural resources.More than 700,000 leaked documents about the billionaire's business empire obtained by BBC Panorama show how she and her husband were allowed to buy valuable state assets in a series of deals.The former president's daughter has made the UK her home and owns expensive properties in central London.She is under criminal investigation by the authorities in Angola for corruption and her assets in the country have been frozen.

'Very serious allegations'

Jaime Esteves was the head of tax at PWC in charge of Portugal, Angola and Cape Verde before leaving the firm.PwC in Portugal, Angola and Cape Verde has 1,500 staff and 42 partners, with 26 partners in Lisbon, 12 in Oporto and 4 in Luanda.The auditing firm told the BBC: "In response to the very serious and concerning allegations that have been raised, we immediately initiated an investigation and are working to thoroughly evaluate the facts and conclude our inquiry."We have also taken action to terminate any ongoing work for entities controlled by members of the dos Santos family."We will be working with our member firms to ensure adherence to the policies we have in place for taking on and maintaining all client relationships and will examine our policies for any necessary improvements."