US Senators are to present evidence that Merrill Lynch knowingly helped Enron set up sham transactions intended solely to create false earnings for the failed energy group.

The Senate hearing into the role of banks in Enron's demise puts Merrill under the spotlight on Tuesday. Much of the questioning will focus on Merrill's role in buying and selling Nigerian power-generating barges in 1999-2000, and whether the deals were real or merely accounting tricks.