Scottish politicians have rejected the UK Government's initial devolution offering - accusing it of selling Scotland short with its "imperfect" plan for more powers.

Holyrood's Devolution Committee - which includes unionist and nationalist MSPs - has unanimously rejected the UK Government's "enduring settlement" for Scotland.

The draft clauses for a new Scotland Bill will not be recommended for legislative consent by the Scottish Parliament in their current state, committee convener Bruce Crawford said at a press conference in Holyrood.

The settlement was drafted by the previous Conservative-Liberal Democrat UK government, in response to the recommendations of the Smith Commission on Devolution convened after the No vote in the independence referendum to deliver on the "vow" of more powers.

But Tory MSP Alex Johnstone today described the draft as "imperfect" and Lib Dem MSP Tavish Scott has demanded the new Tory government "put the full intent of Smith into law".

The committee has recommended a raft of improvements, including the removal of a perceived Westminster "veto" over Scottish benefits, a "triple lock" preventing Holyrood from being dissolved and the right of Scottish ministers to lead international UK negotiations where Scotland has a predominant interest such as fisheries.

Mr Crawford, an SNP MSP, acknowledged that Smith was "carried out quicker than probably people would have wanted" and urged the UK Government to undertake "proper consultation" and present redrafted proposals for Holyrood's consent next year.

Mr Johnstone said fellow unionist politicians must stick to the timetable agreed after the referendum as a matter of priority.

Devolution is expected to be high on Nicola Sturgeon's agenda when she meets David Cameron tomorrow following the SNP's landslide Scottish victory in the general election.

Yesterday, the First Minister described the devolution offer as "a strong starting point" but reiterated her desire to secure "full fiscal responsibility" for Scotland.

She urged the Prime Minister to "demonstrate that Westminster does listen" to Scotland or risk swaying public opinion towards another independence referendum.

The Scotland Office, now led by Tory MP David Mundell, has pledged to hold a full parliamentary discussion "where differing views can be heard".

Speaking at Holyrood today, Mr Crawford said: "The current proposals do not yet meet the challenge of fully translating the political agreement reached in the Smith Commission into legislation.

"The committee is disappointed that the currently proposed legislation sells Smith short.

"Currently, it would not be in a position to be recommended for an LCM (legislative consent motion).

"We are in a discussion now with the UK Government, where hopefully they will recognise that this unanimous process, where all five parties agree, is a serious and mature piece of work that they need to take serious and mature consideration of.

"The UK Government will have an announcement in their Queen's Speech about the timescale of the Bill in recognition that the Smith Commission proposals were, by necessity, carried out quicker than probably people would have wanted."

Deputy First Minister John Swinney, who sat on the Smith Commission, conceded that Smith did not secure sufficient public engagement during its short deliberations.

Speaking at Holyrood general questions, he said it would be beneficial to consult more widely on what Tory peer Annabel Goldie described as "Smith Plus".

Mr Swinney said: "Despite the efforts of Smith to engage widely with the stakeholder community in Scotland ... in my opinion we were not able to sufficiently engage with the wider body politic of Scotland."

Mr Scott, also a member of the Smith Commission, said: "I have no difficulty whatsover in demanding that the full intent of what we agreed on a cross-party basis is implemented by the new UK Government. It doesn't really matter what has happened in the past."

Mr Johnstone said there is a lack of clarity on welfare and benefits.

"What we have here is imperfect," he said.

"The timescale for this whole process was set in the immediate aftermath of the referendum, and there was in that period a significant degree of pressure from one side on the other to stick to that timescale.

"It is, therefore, the priority of those of us who are unionists to make sure that that timescale is to be observed.

"If there is any change to that timescale, that is well outside our remit."

SNP MSP Linda Fabiani said the draft is a recipe for confusion and potential hardship for benefit claimants.