Cuts to vital frontline services will be impossible to avoid if the government slashes town hall budgets, Kent County Council has warned.

The council is bracing itself for bad news this week with the Chancellor George Osborne reportedly preparing to slash council spending by as much as 12%.

The Conservative politician in charge of County Hall’s finances says he fears a further round of government spending cuts could see the county council needing to save as much as £80m over the next two years.

And he has challenged the government to scrap its veto on council tax increases above 2% and conduct a fundamental review of a tax that was “hopelessly out of date.”

Cllr John Simmonds (Con), KCC deputy leader and cabinet finance member, said the government should think carefully before hitting councils.

He said: “To date we have managed savings without significant impact on front-line services as the council has driven out efficiency savings and transformed many of its services.”

“But KCC is not immune from the impact of further funding reductions. If the government wants us to deliver further substantial savings, it will be impossible without significant impact on the delivery of current services.”

Since 2010, Kent County Council has saved over £350 million in response to reductions in government funding - the equivalent of 37% of the council’s net spending.

Cllr Simmonds warned there was a question mark over the amount of money earmarked for social care.

"This is a nightmare scenario for local councils akin to Donald Rumsfeld’s unknown unknowns" - Cllr John Simmonds

“Whilst we welcome the reforms to social care under the act, we are very concerned that no one really knows how much it will end up costing or how it is to be funded. This is a nightmare scenario for local councils akin to Donald Rumsfeld’s unknown unknowns.”

There was a dire need for more money to be allocated to social services in the face of rising costs and growing demand caused by increasing numbers of elderly residents needing care, he added.

In a significant move, KCC said it was now time for the government to give it more freedom over council tax.

Mr Simmonds said: “The county council is committed to ensuring that any future increases are reasonable and take account of household circumstances.”

“But we need to have the ability to raise money in order to protect valued services where we have clear evidence that this is supported by Kent residents without having to arrange a costly referendum.”

The budget this week will be the first fully Conservative budget since 1996.

Experts say spending by the government on councils will have fallen by as much as 50% between 2010 and 2020.