Former bank trader Tom Hayes told British investigators that he was involved in inappropriate attempts at price-fixing with a rival trader, a London court heard Monday.

Hayes, a former UBS and Citigroup trader on trial for trying to rig benchmark interest rates, told investigators with the UK's Serious Fraud Office that he had engaged in what he described as "collusive" behaviour with Deutsche Bank trader Guillaume Adolph. Adolph is one of Hayes's alleged co-conspirators, but he hasn't been charged with any crimes. He has not publicly commented. Deutsche Bank in April settled rate-rigging allegations and admitted wrongdoing.