A future £30bn bill for decommissioning Scottish oil rigs should be paid for by the UK government even if independence goes ahead, Scotland's energy minister said today.

Fergus Ewing told MPs that Westminster had a "moral obligation" to foot the massive North Sea clean-up costs that have been predicted for 2040.

Appearing before the Commons energy committee, the minister insisted a pro-independence referendum win, which is likely to shift the bulk of revenues from North Sea oil to the Scottish Parliament, did not wipe out the past benefits the UK had reaped from the rigs.

Mr Ewing said: "Plainly, given the UK has received £170 billion from oil by rigs that have to be decommissioned, then the UK received the revenue in respect of those rigs.

"It would seem to us reasonable to suggest that having received all the revenue... the costs of (the) accrued revenue, which was accrued entirely in the UK, should in principle be the UK's responsibility."

He added: "In principle, given that the UK has received substantial revenue from these rigs, it seems correct that the UK has a moral and certainly a legal obligation to be responsible for decommissioning."

When pressed further, Mr Ewing said it was possible there could be some form of proposal to share some of the costs.

John Robertson, Labour MP for Glasgow North West, said it was "incredible" that the Scottish Parliament wanted all the revenues from oil reserves while making sure the UK Government "pays for any clean-up in 28 years' time".

He said: "I find that absolutely incredible. Scotland has benefited as much from oil as any area within the United Kingdom."