ALEX Salmond has been fighting on all fronts as experts and opposition parties questioned his plans for immigration, pensions, oil, business and broadcasting in an independent Scotland.

It came as the First Minister prepares to unveil the Scottish Government's independence White Paper on Tuesday which, he told MSPs yesterday, would point the way to "brigher future".

On a testing day for Mr Salmond:

l Labour's shadow minister for immigration, David Hanson, claimed Mr Salmond's promise to increase immigration raised the "frightening prospect" of border posts between Scotland and England.

l Experts warned pensions would be hit if an independent Scotland opted for a different tax and regulatory regime from the rest of the UK.

l A survey by accountants Ernst & Young found eight out of 10 senior oil executives in Scotland feared the industry would be taxed more heavily in an independent Scotland, despite an SNP pledge to the contrary.

l A poll by the Forum of Private Business showed three quarters of small business owners wanted Scotland to remain in the UK.

As questions for the Scottish Government piled up on a frenetic day at Holyrood the pro-independence Yes Scotland campaign even published a list of 75 countries where Dr Who is broadcast, following claims the popular BBC time travel series would cease to be screened in an independent Scotland.

Finance Secretary John ­Swinney, meanwhile, hit back at the First Minister of Wales, Carwyn Jones, after he said he would try to block the SNP's plan for a currency union between an independent Scotland and the UK.

Mr Swinney claimed Mr Jones was only interested in increasing Wales's share of funding at the expense of Scotland. He said: "If Scotland votes No Labour's Welsh leader will be one of the first people asking for a cut to Scottish funding."

Labour's warning of border controls followed clashes at First Ministers Questions when Mr Salmond vowed to increase immigration, in the event of independence, in a bid to boost the economy and offset the impact of the country's ageing population.He said talented overseas students would be allowed to stay and work in Scotland instead of being "kicked out by the UK Border Agency".

But Mr Hanson claimed an independent Scotland, if it joined the UK and Ireland Common Travel Area, would have to pursue similar immigration policies.

He warned: "If the SNP want an independent Scotland to have a radically different immigration policy then he is raising the real and frightening prospect of border posts between the two nations."

Mr Salmond used question time to rebut Labour and Conservative claims that a report from the IFS think tank earlier this week had undermined the case for independence.

The report said an independent Scotland faced higher taxes or spending cuts to bring debts under control over the next 50 years.

But Mr Salmond said: "What happens over the next 50 years will depend on the policies pursued in this country, and that in turn will depend on whether we have got control of the policies pursued in the country.

"I say let's get control of these economic levers, let's increase productivity, increase our exports, invest in our economy, let's grow the Scottish economy and move forward to that better future."

He added: "This party, this Government, has ambition for this country. We think we can invest in the future, grow our economy and give all our people a decent future."

A spokesman later accused the SNP's opponents of peddling scare stories, including a "bogus" claim Dr Who would not be shown on a new national broadcaster set up after independence.