The European Commission's former chief accountant, who claimed there were holes in the EU budget system, says she will fight against her sacking.
Marta Andreasen says people do not trust the Commission
Marta Andreasen was fired on Wednesday, two years after she was suspended for disloyalty and breach of trust.
The Spanish official went public in 2002 with claims that the EU's 100bn euro (£69bn) budget was open to fraud and abuse.
Mrs Andreasen's supporters regard her as a scapegoat and a whistleblower.
She was brought in as chief accountant in 2002, not long after the EU executive
led by Jacques Santer was brought down by a financial scandal in 1999.
By August 2002 she had sent an internal letter to Commission President, Romano Prodi, expressing her concerns about failures in the accounting system. She later went public and was suspended.
Chris Heaton-Harris MEP, who led the campaign to defend Mrs Andreasen, said her sacking was a "vindictive move from a failed Commission".
"All Marta Andreasen did was do her job properly. She informed Neil Kinnock and his colleagues of her concerns, yet Neil Kinnock's response was to suspend her and now sack her," he said.
"The Commission has again persecuted another whistleblower whose only crime was to stand up and raise concerns on the EU's accounting procedures."
The UK's Neil Kinnock was the commissioner in charge of administrative reform at the time.
He said then that Mrs Andreasen was suspended not for the act of whistleblowing itself, but for failing to follow the EU's whistleblowing procedures.
He added that her behaviour would not have been tolerated by any civil service in the democratic world.
In a statement released on Wednesday, the Commission said she had "repeatedly and knowingly acted in disregard of her obligations", adding that she had failed to seek authorisation for public statements that were unsubstantiated.
Mrs Andreasen, who says she will continue to fight her sacking, believes time will prove that she was right to suggest that the EU's accounting system was open to fraud.
She said the commission was wrong in claiming that she had failed to observe the proper procedures, arguing she raised her concerns repeatedly with her superiors before being suspended without notice.
"If Europe wants to advance... it has to have trust in its governing institutions. I believe I can be trusted. The people don't trust the Commission," she told French news agency AFP.