Environmental campaigners have attempted citizen’s arrests of the chief executive and chief financial officer of Thames Water on suspicion of causing a causing a public nuisance.

The campaigners accuse Chris Weston and Alastair Cochran of five to seven counts of the offence, which is regularly used against protesters, including illegal discharge of sewage, mismanagement of customer funds and operating unsafe infrastructure.

They say they have worked with lawyers to draw up a draft indictment supporting their allegations, which they intend to submit to prosecutors.

Their action came as the Guardian revealed Thames Water increased the amount of raw sewage it was discharging from its system into England’s rivers by a record 50%, and in the week the company won approval from the court of appeal for a £3bn emergency debt bailout to avoid financial collapse.

Meanwhile, households across the UK are expecting increases in water bills of up to 35%, with Thames Water seeking a hike of 59%.

Weston enjoys a pay package of up to £2.3m a year, the campaigners noted in a statement. “These execs are earning huge sums of money each year [while] personally allowing raw sewage to continue being dumped in our waters,” said Rachel Whyte, who issued the arrest.

“Time and again we see them get fined, but nothing changes other than the increase in our bills. It should be a crime to extort the public like this. If accountability isn’t going to be delivered by regulators and the government, then I feel it is my duty as a citizen to do this.”

According to their statement, a group of campaigners, all women, entered the lobby of Thames Water’s offices in Reading, Berkshire, on Tuesday morning, where they called for Weston and Cochran to come down to be served with draft indictment papers and a dossier of evidence.

Weston came down to the building’s lobby after police officers arrived. The activists had notified Thames Valley police of the action they planned to take, and requested it send officers to arrest Weston and Cochran. They did not, but the activists claimed the officers reviewed their dossier of evidence and took it away for further investigation.

Whyte continued: “We intend to charge two senior executives of Thames Water with public nuisance. We are working with lawyers, and now the police, to make this happen.”

Thames Valley police were contacted for comment.

A spokesperson for Thames Water said no arrest had been made “and neither the CEO nor the CFO met with any of the individuals”, adding: “Police attended the office and requested that this group leave the property.”