Ms Alexander leads the largest opposition party at Holyrood

It made the claim in a letter to the Holyrood allowances review.

Labour pointed out that the opposition leader at Westminster receives a special allowance of �644,000 - while Ms Alexander receives �22,000 a year.

The party claims that is not enough to employ a private secretary or properly scrutinise the government's policies.

We are being forced to look at external and/or party sources of funding to meet the demands of the leader's post Sarah Metcalfe Scottish Labour

The support given to Labour as the main opposition at Holyrood runs to �247,000, while the Conservatives receive just under �4m at Westminster.

In a submission to the review Sarah Metcalfe, Labour's research and strategy director, said the party was required to hold to account an SNP government which had the entire civil service at its disposal.

She said: "We are being forced to look at external and/or party sources of funding to meet the demands of the leader's post and even consider whether [the] members support allowance could be used, which is properly intended to support her work as a constituency member.

'Paid directly'

"Such an approach does not serve the interests of either parliament or probity."

Scottish Parliament officials pointed out that Labour this year qualified for a �21,813 leader's allowance, which is calculated on a pro-rata basis.

The SNP's submission to the inquiry also pointed out the gap between MP and MSP allowances.

"Salaries and costs for staff should be separated and removed from MSPs' members support allowance," added SNP Holyrood group convener Gil Paterson.