Those charged as part of a 15-year-old inquiry into the assets include Pascaline Bongo, 66, his eldest daughter and former director of his cabinet, Omar Denis Jr Bongo, 28, who is also the grandson of Congolese President Denis Sassou Nguesso, Jeanne Matoua, 38, and Joseph Matoua, 40, the source said, confirming a report by Africa Intelligence. It was not immediately clear who the fifth child was.
Investigators say the Bongo siblings were involved in a fraudulently constructed real estate scheme said to be worth some 85 million Euros.
Pascaline Bongo's lawyer, Corinne Dreyfus-Schmidt, said the charges involved "legal and factual anachronism".
Omar Denis Jr Bongo's attorney, Jean-Marie Viala, rejected the allegations against his client.
France earlier this year filed charges against four other of his children, Grace, Betty, Arthur and Hermine Bongo, by investigators probing financial crimes including concealing embezzlement of public funds, corruption and misuse of company assets.
Those charged deny any criminal activity or involvement in government malfeasance.
Omar Bongo was the second President of Gabon from 1967 until his death in 2009, a total of 42 years. He was succeeded by his son Ali.
Bongo had three wives and 54 children.