Amy Schumer has said she believes money is at the heart of the ongoing US debate over gun control.

The star of hit comedy Trainwreck last week signalled her determination to speak out against gun violence following the fatal shooting of two cinemagoers at a screening of her film in Louisiana on 23 July. She appeared on stage with her second cousin, New York senator Chuck Schumer, to promote a three-part plan aimed at making it more difficult for violent criminals and mentally ill people to obtain firearms in the US.

Speaking at the Locarno film festival in Switzerland, where Trainwreck screened on Saturday night, Schumer was asked why the US struggled to manage its firearms problem. "I think it's money," the actor replied. She said she had decided to campaign against gun violence because the killings last month "really upset me", adding: "It felt really personal to me. In terms of what's going on in our Congress and why this has been such an ongoing issue it is very frustrating."

John Russel Houser, 59, described as a "drifter" with a history of mental illness, killed Jillian Johnson, 33, and Mayci Breaux, 21, and injured nine others during the screening at a cinema in Lafayette, Louisiana, before turning the gun on himself. The Schumers' proposed legislation would punish US states that fail to submit relevant records into a background check system while rewarding those that comply.