Irish Water has been warned that it may not be legally able to scrap charges.

Under European law, there is no option to return to supply the service for free, according to legal advice received by the company.

There is an EU water directive in place, and the charges cannot now be reversed since their introduction under the previous government.

Water charges are seen as a stumbling block to potential coalition talks between Fianna Fáil and Fine Gael who hold opposing positions on payment.

Anti Austerity Alliance TD Paul Murphy (pictured) said the legal advice was commissioned by Irish Water after the general election.

He added he was not confident Micheál Martin's party would stick to its anti-water charges stance.

"I don’t trust Fianna Fáil as far as I can throw them," he said. "I think they may be willing to negotiate away opposition to water charges in exchange for something else - cabinet positions or whatever.

"We can’t wait for them to negotiate a programme for government by themselves.

"The only way to ensure abolition (of Irish Water) is to step up the boycott (of charges) and a massive united demonstration on the streets."