The Senate Finance Committee’s top Democrat has called for the US government’s ethics watchdog to look into whether Treasury Secretary Steven Mnuchin’s recent comments about The Lego Batman Movie constitute an ethics violation.

Senator Ron Wyden said in a letter to Office of Government Ethics Director Walter Shaub (via Reuters) that he is concerned Mr Mnuchin broke his ethics agreement on Friday, when he suggested people go to see a film produced by one of his companies.

Asked for a movie recommendation by news website Axios, Mnuchin joked: "I'm not allowed to promote anything that I'm involved in. So I just want to have the legal disclosure, you've asked me the question, and I am not promoting any product. But you should send all your kids to Lego Batman."

The treasury secretary agreed to divest his interests in Ratpac-Dune Entertainment Holdings LLC, which is also behind Avatar and Max Max: Fury Road, within 120 days of his confirmation, and "not participate personally and substantially in any matter that has a direct and predictable effect on the financial interests of the entity”.

Mr Wyden wrote in his letter: ”I am concerned that Sec. Mnuchin’s comments, may be seen to have a predictable effect on the financial interests."