Sean Thornton, a former chief counsel at Treasury's Office of Foreign Assets Control, will become legal counsel for Paribas' U.S. sanctions compliance group, one of the people said. He will head the Group Financial Security U.S. legal team.

BNP Paribas in June agreed to pay U.S. authorities $8.9 billion and to plead guilty to criminal charges for conspiring to violate sanctions on Sudan and other countries, in part by stripping information from wire transfers so they could pass through the U.S. system without raising red flags.

Thornton's hiring symbolizes the bank's commitment to beefing up compliance personnel and operations, one source said on Thursday.

Reuters previously reported that BNP was relocating its U.S. sanctions compliance operations to New York from Paris.

Reached by cellphone on Thursday, Thornton said he was on vacation and declined comment. A BNP spokeswoman also declined comment.

Sanctions compliance involves screening and analyzing transactions to make sure they do not run afoul of U.S. laws that bar moving money on behalf of certain entities and countries such as Iran and Sudan.

Thornton was most recently counsel at the law firm of Skadden, Arps, Slate, Meagher & Flom LLP in Washington. He left Skadden on Friday, sources said, and will start at Paribas at the end of the month.

Thornton served as OFAC's chief counsel from 2005 to 2012, where he helped develop the legal framework for U.S. economic sanctions with Iran, according to his biography on the Skadden website. He also played a leading role in landmark settlements with international banks over violations of U.S. sanctions, the bio said. 

The ex-government lawyer joined Skadden in 2012. At the firm, his practice focused on laws and policies underlying U.S. economic sanctions, as well as anti-money laundering, the bio said.

Skadden was among the law firms retained by BNP as the bank negotiated with U.S. authorities over sanctions violations. Sullivan & Cromwell and Cleary Gottlieb Steen & Hamilton also represented the bank.

(Reporting by Karen Freifeld, Editing by Karey Van Hall and Andre Grenon)

By Karen Freifeld