(Reuters) -U.S. investment firms Silver Point Capital and Elliott Management are formulating a 10-billion-pound-plus ($13.53 billion) rescue package for Britain's Thames Water, Bloomberg News reported on Friday, citing people familiar with the matter.

The deal will comprise a major debt overhaul, including a multi-billion-pound haircut for senior creditors, in addition to reductions already expected for junior Class B bonds, loans and around 3 billion pounds in holding company debt, the report said.

The rescue package will provide an equity boost of between 3 billion pounds and 4 billion pounds to stabilize the utility's finances, according to the report.

"The Creditors have submitted a detailed long-term turnaround plan that will fix the root causes of Thames Water's problems, restore its balance sheet, rebuild customer trust and fix the fundamentals of the business once and for all," a spokesperson for the creditors, which include Silver Point Capital and Elliott, said in an emailed statement to Reuters.

Thames Water did not immediately respond to a request for comment.

Thames Water suffered a major setback on Tuesday in its fight to avoid nationalisation, as it said U.S. private equity firm KKR had pulled out of a multi-billion-pound rescue plan.

Britain's biggest water supplier is at the centre of a public backlash against the privatised water sector, which has been blamed for polluting Britain's rivers and seas while hiking bills and prioritising dividend payouts over infrastructure investment.

($1 = 0.7393 pounds)