Scottish ministers have been told “the ball is in your court” in the controversy over how to fund greater tax and welfare powers for Holyrood.

Experts have warned that how money gets carved up between London and Edinburgh could cost Scotland £1 billion a year.

Earlier this month an influential committee of peers even urged David Cameron to halt his flagship Scotland Bill, currently going through Westminster, warning that "nobody knows what is going on".

The so-called 'fiscal framework' will decide how much money passes between the Treasury and the Scottish Government.

But Scottish ministers have warned they could block greater devolution if they believe the deal damages Scotland.

The Chancellor told MPs the devolution proposals had to be “underpinned by a fiscal framework that is fair to all taxpayers”.

In a direct appeal to Scottish ministers, he added: “And we are ready now to reach an agreement - the ball is in the Scottish Government's court. Let's have a deal that's fair to Scotland, fair to the UK and that's built to last."

Both sides later played down the comments.

Conservative Scottish Secretary David Mundell accused Scottish ministers of “posturing” but said he had confidence in Deputy First Minister John Swinney.

"What we are saying is this is a negotiation and you are part of that negotiation," he added.

"Some of the comments we have seen recently from the Scottish Government and SNP MPs would rather suggest that the framework was taking place in a parallel universe; it's not, they are a party to a negotiation.

"They need to set out what it is they want in the negotiations within the negotiations.”

Scottish Government sources said they were currently focussed on their budget, due to be unveiled within weeks, "and will step up negotiations after that”.

Both the Chancellor and the Prime Minister also the SNP's aim of independence, saying it would prompt much deeper public spending cuts.

David Cameron said it would be "cuts, cuts, cuts, taxes, taxes, taxes, with no relief from the National Lottery”.

A report by the Institute for Fiscal Studies (IFS), the University of Stirling and the Centre for Constitutional Change, funded by the Nuffield Foundation, has warned that the options for amending current arrangements could leave Scotland short by as much as £1bn a year after a decade.

Leading Scottish economist Professor Anton Muscatelli, the Principal of Glasgow University, also warned the wrong framework could cost Scotland millions.

Mr Swinney , the , has said that Scottish ministers would support the Scotland Bill only "if there is a satisfactory and fair fiscal framework agreed between the Scottish and UK Governments. We will never sell the people of Scotland short."