THE Bill legalising same-sex marriage is to be fast-tracked through Holyrood, beginning with the first evidence session starting early next Thursday with the aim of achieving Royal Assent for the legislation by next March.

In an unusual move, MSPs will hold double sessions starting earlier in the day just to get through the weight of information from a broad spectrum of organisations and individuals who have been asked for their views on shaping the new laws.

The Scottish Government faced accusations earlier this year that the equality legislation was slipping behind schedule and progress at Westminster for similar reform, but Ministers succeeded in publishing the Bill before the summer recess and have made clear that they expect the new law to be expedited as soon as possible.

A Government source said: "After previous accusations about delays you can be sure that there will be no hold-ups on this."

But John Deighan, a spokesman for the Catholic church in Scotland, said of the timescale: "You can only see this as undue haste. It looks like a bandwagon that no-one has been minded to take in the right direction.

"They ought to remember that if you make law in haste you do not get the best legislation."

The suggestion within Government is that limited numbers of civil servants compared to numbers at Whitehall hampered progress at Holyrood, but it is claimed that once the Bill was published in June there was nothing to stop Scotland forging ahead with legislation.

Holyrood's Equal Opportunities Committee will begin consideration of the Bill next Thursday with the first of several double evidence sessions which will begin at 8.30am in order to get through business before full sessions of the Parliament start.

On that day alone they will get over the two sessions: Stonewall Scotland, LGBT Youth Scotland, Religious Society of Friends (Quakers), the Equality Network, and the Scottish Transgender Alliance, followed by a second panel of the Muslim Council of Scotland, the Methodist Church in Britain, Scottish Catholic Parliamentary Office, and the Evangelical Alliance Scotland.

The following week there will be two equally busy panels drawn from both sides of the debate. Questions have been raised about the way in which a Parliament with just 129 members and a strict rule that committees cannot meet when the full Chamber is in session, can cope with demanding legislative scrutiny.

But welcoming the approach being taken to the Marriage and Civil Partnership (Scotland) Bill, Green Party co-convener Patrick Harvie said: "All the way along there have been Labour folk critical of the timescale for this Bill, but it was introduced before recess so there should not be a problem.

"The only thing that would concern me now is if the Government began giving away concessions on wider civil liberties. I don't think that's likely. It looks like some people are just going to have to accept they have lost the argument."

A Scottish Government spokesman said: "The Bill is proceeding on schedule with wide cross-party support. The Scottish Government is committed to a Scotland that is fair and equal and that is why we believe same-sex couples who wish should be allowed to marry as soon as possible.

"Following Royal Assent the Scottish Government will implement provisions for the bill and make an Order under the Scotland Act 1998 to allow the Equality Act 2010 be amended to provide further protection for religious and belief celebrants. These actions will be undertaken at the same time."