Washington: Special prosecutor Robert Mueller is bolstering his team of investigators probing possible collusion between the Trump campaign and Russia, adding a top Justice Department official overseeing active investigations into corporate fraud and foreign bribery, according to people familiar with the matter.

The official, Andrew Weissmann, is the most senior government official to join Mueller, the former Federal Bureau of Investigation director who became special counsel on May 17, said two people, who asked not to be named discussing a personnel matter that hasn't been made public.

Mueller recently brought on Peter Carr, a veteran spokesman for the Justice Department, to deal with the news media. He also hired at least two lawyers from his former law firm, Wilmer Cutler Pickering Hale & Dorr LLP.

As the head of the Justice Department's fraud section in the Obama administration, Weissmann's specialties have included corporate wrongdoing and foreign corruption. He has overseen investigations into Volkswagen AG over diesel-cheating, global banks over market manipulation and Brazil's state-owned oil company Petrobras over corrupt payments. He also started a pilot program that offered companies incentives to self-report possible violations of the Foreign Corrupt Practices Act, which prohibits bribing foreign officials.