Two anti-corruption groups have started legal action aimed at wrecking a controversial plea bargain reached between the U.K.’s Serious Fraud Office and arms company BAE Systems.

The SFO had spent years investigating suspicions that BAE used bribery and corruption to secure deals worth billions of pounds in several countries, but ten days ago it unveiled a deal that would see the company plead guilty to a charge of poor recordkeeping and accept a fine of just £30 million ($47 million).

The company agreed to a linked settlement with the U.S. Department of Justice that will see it admit a charge of conspiring to make false statements to the U.S. Government and pay a fine of $400 million.

When the deal was announced, two pressure groups, Campaign Against the Arms Trade and The Corner House, said they were “shocked and angered” by a deal in which the company was only admitting “an accounting misdemeanor” in the U.K.

They have now started legal proceedings to request a judicial review, where an independent judge will decide whether the SFO was right to agree the plea.

The campaigners claim that the SFO failed properly to apply its own prosecution guidance because the plea deal fails to reflect the seriousness and extent of BAE's alleged offending.

They argue that the SFO has unlawfully concluded that factors weighing against prosecuting the more serious charges of corruption outweigh those in favor of prosecution.

“Plea bargains should only ever be entertained when companies have really come clean. BAE has not,” says Nicholas Hildyard for The Corner House. “Once again, an SFO decision has reinforced the U.K.'s reputation for letting big companies get away with bribing. Once again, it has shown a blatant disregard for the rule of law.”

The Campaign Against the Arms Trade said it has received a response to its claim from the SFO, which its lawyers are now considering.

The SFO would not comment on the allegations in the judicial review claim. A spokesman said that the “wheels were in motion” for the plea agreement to go before the criminal courts for approval and the agency would be pushing ahead as planned. The deal needs to go before a Magistrates Court and then a Crown Court, which could take several months.