Both the Italian and EU regulators gave the go-ahead for the takeover bid, which will see BNP Paribas purchase 48 per cent of the company from BNL shareholders by the end of June, followed by a bid for the remaining shares.
In a statement, BNP Paribas said that the current offer of â¬2.925 ($3.611) per share would stand until May 16th.
The purchase is set to be the biggest deal for the Paris-based bank since the merger of BNL and Paribas banks in 1999.
The takeover of BNL, Italy's sixth largest banking institution, will be only the second time that a foreign company has taken control of a major Italian bank, following the purchase earlier this year of Banca Antonveneta by Netherlands-based ABN AMRO.
BNP Paribas says it intends to keep BNL's name, as well as its headquarters in Rome, and BNL's current chairman has agreed to remain in his post at the request of BNP executives.