The Scottish Parliament will today vote against Theresa May's proposed Brexit deal, with MSPs calling instead for a "better alternative" to the PM's plans be taken forward.

Four of the five Holyrood parties - the SNP, Labour, the Greens and Liberal Democrats - will unite to back a joint motion, which also makes clear their opposition to a no-deal Brexit.

Constitutional relations secretary Mike Russell said the debate was a "historic opportunity for the Scottish Parliament to come together and formally oppose both a 'no deal' option and the Prime Minister's damaging Brexit deal".

But the Tories, who will be the only party to vote against the motion, claimed the SNP and Scottish Greens were using the debate to try to push for a second vote on Scottish independence.

The vote comes six days ahead of the "meaningful vote" at Westminster, when MPs will have their say on the PM's Brexit deal.

While Holyrood voting against the proposals will not affect proceedings in the House of Commons, it will put the Scottish Parliament on record as opposing both the agreement and the prospect of a no deal Brexit.

The joint motion argues the draft withdrawal agreement and political declaration will be "damaging for Scotland and the nations and regions of the UK as a whole and therefore recommends that they be rejected and that a better alternative be taken forward".

Speaking ahead of the debate, Mr Russell said: "The Prime Minister's Brexit deal will make Scotland poorer and deliver continued uncertainty. It will mean years of further negotiations with no guarantee that a trade deal with the EU will even be agreed.

"This is a historic opportunity for the Scottish Parliament to come together and formally oppose both a 'no deal' option and the Prime Minister's damaging Brexit deal."

Scottish Government analysis of the PM's draft deal to leave the European Union indicated it could result in an annual loss of £1600 to everyone in Scotland.

Meanwhile separate documents published by the UK Government showed it could cut the country's GDP by up to 3.9% over the next 15 years compared to staying in the EU - while a no-deal Brexit could cause the economy to shrink by 9.3% over the same period.

Mr Russell said: "The UK Government's own analysis, as well as the detailed assessment from the Scottish Government, shows why the draft Brexit deal is unacceptable - it would make us poorer while extending uncertainty."

After "cooperation" by different parties to draw up a joint motion, he added Holyrood should "now reach a consensus and oppose both the proposed draft Brexit deal and the suggestion a no-deal Brexit is the only alternative".

The Scottish Conservatives said they were the only party "committed to respecting the results of both referendums we have held in the last four years".