THE GMB union has called for Britain’s biggest water firm to be nationalised if shareholders won’t agree to reduce its spiralling debts.

Thames Water warned today that turning around the company would “take time” as it revealed a 54 per cent drop in profits and 7 per cent rise in debts to £14.7 billion in the six months to October.

In June, then chief executive Sarah Bentley stepped down abruptly amid concerns over the firm’s financial security as it emerged that ministers were drawing up contingency plans for emergency nationalisation if it collapsed under the weight of the massive debt burden.

GMB national officer Gary Carter said: “Thames Water must come clean on the company’s finances.

“It’s clearly struggling under a mountain of debt and desperately needs investment, not loans.

“Shareholders have to put their hands in their pockets and spend the money needed to stop the pollution and clean up our waterways.

“With hundreds of job losses already announced this autumn, it’s clear Thames cannot cut its way out of the crisis.

“If shareholders aren’t willing to stump up the cash, Thames should be brought back into public ownership.”

Interim bosses at the troubled utility giant admitted that “immediate and radical action” was needed to improve its environmental and financial performance.

The auditors of Thames Water’s parent company Kemble Water Holdings have warned that it could run out of money by next April if shareholders do not pump in more cash.

PricewaterhouseCoopers said last week that there was a “material uncertainty” over the future of Kemble, amid concern that there are no plans in place to refinance a £190 million loan at one of its subsidiary companies.

Thames Water Utilities said: “We are in a robust financial position and are extremely fortunate to have such supportive shareholders.”