THE package of new powers for Holyrood set out by the Smith Commission are incoherent and unsustainable, leading academics have warned.

Giving evidence to Holyrood's devolution committee, the cross-party process was also criticised for being rushed, leaving too little time for public consultation.

The new powers, revealed last month, have been hailed by pro-union parties as delivering on 'the vow' of further devolution for Scotland, made in the run-up to the independence referendum. However, the SNP and the Greens have criticised the package for not going far enough.

The experts raised concerns over how the devolution settlement, including control of income tax and some responsibility for welfare, would work in practice.

Michael Keating, professor of politics at the University of Aberdeen, said: "I don't think they amount to a coherent package and the fundamental problem is the circumstances in which the Smith Commission was set up and the timetable that it was given.

"This has not allowed the kind of material consideration, public debate, civil society input or research that would be required to put together a coherent set of proposals.

"We know the political circumstances in which the vow was made and the timetable was set, but it doesn't make for good policy-making."

Concern was also raised that the Scottish Parliament could become less independent as a result of the deal.

Professor Nicola McEwen, a politics and devolution expert based at the University of Edinburgh, said: "This increases the powers of the Parliament but at the same time makes the Parliament more dependent in a way, because of the direct interdependencies in tax policy and welfare policy, and that will create some challenges."

She said she believed the agreement was implementable but added: "I don't think it's sustainable."

The UK Government has said that that legislation on devolution is on course to pass by early 2016. The Secretary of State for Scotland, Alistair Carmichael, has said he favours transferring the powers in one batch, with the exception of votes for 16 to 17-year-olds.

Meanwhile, the Scottish Government has called for the powers which do not require primary legislation to be transferred sooner.

David Bell, professor of economics at the University of Stirling, raised concerns about the transparency of the Barnett Formula, used to distribute central funds between the nations of the UK, and the potential for "gaming" within it.

He said: "There is a need to make the way that the whole system works much more transparent because we're still going to be relatively exposed to decisions made at Treasury level about how the formula works in practice."