Citizen Zhukova registered marriage with a citizen

Citizen Zhukova registered marriage with citizen Ivanov in July 2008. In April 2011, a lawsuit was filed in court in a lawsuit filed by the prosecutor to declare the marriage between Zhukova and Ivanov invalid. The prosecutor explained his demand by the fact that in 2005 Ivanov registered a marriage with a citizen Vakulenko, who has not yet been terminated. When registering a marriage with Zhukova, Ivanov hid this fact from her. There was no mark in the passport of citizen Ivanov about his first marriage. Ivanov received his passport in 2000 in connection with the loss of the former, and when it was issued, he did not make a mark on his state of marriage.
What principle of family law was violated by Ivanov when he married a citizen Zhukova? Does the prosecutor have the right to demand recognition of marriage invalid in the considered situation? What are the grounds for declaring marriage invalid.