ALEX Salmond was last night accused of trying to "shut down" the debate on Scottish independence because he was afraid the true costs would scare the public and scupper the SNP's core policy.

In the latest in a series of attacks on the First Minister, the Liberal Democrat Scottish Secretary Michael Moore also challenged Salmond to set out his timetable for an independence referendum when Holyrood returns from holiday this week.

On Wednesday, Moore used a speech in Edinburgh to demand Salmond explain what independence would mean in six areas: bank regulation, currency, EU membership, defence, pensions and total costs.

The following evening, Danny Alexander, the LibDem Chief Secretary to the Treasury, delivered a second attack, claiming Scotland would immediately inherit a £65 billion share of the UK's national debt if it left the union.

Alexander's visit to CBI Scotland also saw business leaders warn that uncertainty over the timing, wording and legality of an independence referendum could deter investment.

CBI Scotland chairwoman Linda Urquhart warned of "possible damage" to Scotland over the issue.

The words provoked a ferocious response from the SNP, with Treasury spokesman Stewart Hosie MP denouncing the CBI for making a biased and "politicised attack".

Last night, Moore suggested such SNP anger was largely a diversion as it tried to avoid awkward questions.

He said: "The UK Government and CBI Scotland have asked serious questions about independence but these have been met with irritation rather than answers. That's a real shame: the Scottish Government should welcome the debate on independence, not seek to shut it down."

He said the CBI had "every right to ask questions about independence and what this would mean for Scottish business, jobs and security".

CBI Scotland has also warned it will not back calls by the Scottish Government for corporation tax powers to be devolved. It has lodged concerns over the proposal in response to a discussion paper published by the Government.

The business group said it had "long believed" the interests of the UK, including Scotland, were best served by a unitary corporation tax system.

However, a Scottish Government spokesman insisted having full responsibility for corporation tax would give firms north of the Border a "competitive edge".

Salmond is due to set out his legislative programme for the new Parliament on Wednesday.

Moore said that was an ideal opportunity for the First Minister to answer his six questions and "front up [his] thinking on independence".

So far, the First Minister has only said a referendum on separation would be in the second half of the five-year Parliament.

A spokesman for Salmond said: "Michael Moore seems confused – he began last week saying the Scottish Government was talking too much about the constitution, and now he claims we are not saying enough about the urgent need for more powers for our national Parliament.

"He seems to have ditched the LibDems' own policy of more powers for Holyrood and is now just acting as a front man for a Tory Government Scotland didn't vote for."

Lord Wallace of Tankerness, the former deputy LibDem First Minister and current Advocate General, yesterday claimed Salmond doesn't actually want independence, and would settle for increased powers.

In a newspaper interview, he said: "The First Minister is a very forceful character and someone who in spite of all the rhetoric about independence actually knows on which side the bread is buttered and therefore will push for maximum powers but stop short. I wouldn't say he was a feartie but he's got his head screwed on the right way."

Willie Rennie, leader of the Scottish LibDems, also joined the constitutional debate, announcing plans for a commission on Scottish home rule to head off independence. The new body would propose a "distribution of powers" between London, Edinburgh and councils.

The surge in activity by the junior Coalition party follows a meeting of the so-called "quad" – David Cameron, George Osborne, Nick Clegg and Alexander – last week.

The more aggressive tone also heralds legislative developments at Westminster, where the Scotland Bill begins detailed consideration in the Lords on Tuesday. The bill includes the transfer of enhanced powers over income tax, and new borrowing powers, but the SNP have called for it to also include extra powers on corporation tax, excise duty, broadcasting, Europe and The Crown Estate.

Before the summer, Moore stressed to Salmond the Coalition was in listening mode, but the tone and timing of Wednesday's speech to the David Hume Institute suggest he is about to reject most of the SNP demands.

In theory, the SNP majority at Holyrood could refuse to endorse the Scotland Bill, but UK Government sources believe it will win grudging support from Holyrood, as the SNP need its limited borrowing powers to help build the second Forth Road Bridge.

CBI Scotland last night issued a detailed critique of the SNP plan to devolve corporation tax, saying it could not support it. Salmond has repeatedly called for the tax to be set by Edinburgh, so it could be cut from 26% to nearer the Irish Republic's ultra-low 12.5%.

However, reaffirming its preference for a unified UK tax system, CBI Scotland suggested Scottish ministers use their existing powers to cut business rates instead.

Labour said the rebuff was "hugely significant". The SNP have criticised Moore and Alexander for making weak and tired points, and failing to present a positive case for the Union.

But with a referendum at least three years off, the Coalition is playing a longer game. The battle has begun. It has a long way to go.