Researchers from the University of Canterbury in New Zealand claim that the building brick products are less “innocent” than they used to be.
They say that more war-like scenarios were being featured in theme kits and weapons were now commonplace in 30% of kits.
Lead researcher Christop Bartneck said: “The Lego company’s products are not as innocent as they used to be.
“The violence in Lego products seems to have gone beyond just enriching game play.”
Having examined Lego catalogues from 1973 to 2015, the research stated in online journal PLOS ONE: “Currently, around 40% of all pages contain some type of violence — scenarios involving shooting and threatening behaviour have increased over the years.
“The atmosphere of the violent acts is predominantly perceived as exciting.”
The team say the increased violence is down to Lego’s attempt to maintain children’s attention in the digital age.
The study added: “To catch the attention of their customers, toy manufacturers are similarly locked in a metaphorical arms race for exciting new products.”
Lego spokesman Troy Taylor said that the company’s products were simply reflective of how a child develops.
He said: “As with other play types, conflict play is a natural part of a child’s development.
“We always try and use humour where possible as it helps tone down the level of conflict.”
Lego said it was a record-breaking year for the brand, with an estimated 100m children in 140 countries playing with Lego bricks and other toys.