(Adds further comment from Standard Chartered)
By Stephen Eisenhammer and Lawrence White
LUANDA/LONDON, March 28 (Reuters) - The $500 million at the centre of an alleged fraud involving the son of Angola's former president was transferred out of a Standard Chartered account held by Angola's central bank, the British bank told Reuters on Wednesday.
The Angolan prosecutor general's office said on Monday it had charged Jose Filomeno dos Santos, the former president's son, and Valter Filipe da Silva, the former governor of the central bank known as Banco Nacional de Angola, with fraud over the case.
Britain's National Crime Agency said last week that $500 million had been frozen in the UK as part of an investigation into a potential fraud against Angola's central bank and could be returned to the southern African country.
"We are aware that our client, Banco Nacional de Angola (BNA), was the victim of an attempted fraud in Angola which involved the transfer of funds from their Standard Chartered Bank account," Standard Chartered said in an emailed response to questions.
"We understand the fraud was not successful and that BNA is conducting its own investigation and has now recovered the monies," Standard Chartered added.
The bank did not respond to a question on how the transaction appeared to bypass security mechanisms.
The Angolan central bank, which has so far made no public statement about the case, did not immediately respond to a request for comment.
Dos Santos is the highest profile figure charged since President Joao Lourenco succeeded longtime leader Jose Eduardo dos Santos last September pledging to tackle an endemic culture of corruption in the oil-producing country.
Reuters was unable to immediately contact Jose Filomeno dos Santos. He said in a statement circulated in Angolan media on Tuesday that he was cooperating with the investigation and had handed his passports in to the prosecutor general's office.
Reuters has also been unable to reach Da Silva for comment.
Standard Chartered said it is closely cooperating with Angola's central bank and British law enforcement.
A source familiar with the matter told Reuters on Wednesday that HSBC had frozen a bank account in connection with the alleged fraud.
The Financial Times, which reported the HSBC bank freeze earlier, said documents purporting to be from Swiss bank Credit Suisse were also used in the fraud.
The documents were fake and Credit Suisse was not involved in the transaction, a source familiar with the matter told Reuters.
Britain's National Crime Agency said the funds were frozen after the transaction raised suspicions, without naming the banks involved.
Standard Chartered, which has operations across Asia and Africa, ended its dollar-clearing operations with commercial banks in Angola in Dec. 2015 because it deemed it too risky.
Singapore said last week its central bank had imposed penalties of nearly $5 million on Standard Chartered Bank and Standard Chartered Trust (Singapore) for breaching money laundering rules and terrorism financing safeguards.
HSBC's move to freeze the accounts and work with authorities to return the funds will reinforce the lender's assertion that its efforts to improve financial controls are bearing fruit.
The bank paid $1.9 billion in fines to U.S. authorities in 2012 and agreed to install an independent monitor to improve its anti-money laundering controls, after it was used to launder Mexican cartel drug money.
A five-year period in which the bank faced criminal prosecution if it breached U.S. compliance rules again ended in December. (Reporting by Stephen Eisenhammer in Luanda and Lawrence White in London; Editing by Adrian Croft)