NatWest Markets pled guilty and agreed to a $35 million fine to settle US criminal charges that it committed fraud in the Treasury bond market, the Department of Justice announced Tuesday.

US authorities described the British financial heavyweight as a "repeat offender" because the violations breached earlier settlements with the company formerly known as RBS Securities.

"As we have previously warned, there will be serious consequences for a company that breaches the terms of an agreement with the government," said Deputy Attorney General Lisa Monaco. "Today's guilty plea by NatWest and the associated penalty show exactly that."

NatWest Markets pled guilty to two counts of fraud connected to "spoofing" in the giant US Treasury market.

Traders with the group placed orders with the intent to cancel the transaction in order to artificially push the market up or down. The traders then made money off these price movements.

NatWest Markets will pay $35 million and plead guilty to fraud in the US Treasury market
NatWest Markets will pay $35 million and plead guilty to fraud in the US Treasury market AFP / NIKLAS HALLE'N

The trades took place between 2008 and 2014 and over approximately three months in 2018, the Justice Department said in a court filing.

"For over six years, NatWest engaged in separate fraud schemes to manipulate the market and unlawfully enrich themselves," said US Postal Service Inspector Eric Shen.

The Justice Department said the conduct violated a 2017 non-prosecution agreement over NatWest's fraudulent mortgage-backed securities trading, and occurred while it was on probation following a 2015 guilty plea for conspiring to manipulate the foreign exchange market.

"We deeply regret the past behavior of a small number of former employees, which has led to today's guilty plea," said Robert Begbie, chief executive of NatWest Markets.

"The behavior of these individuals was unacceptable and has no place in the bank we are today."