Labour argued that the establishment of a Scottish Parliament and Assemblies in Northern Ireland and Wales would see off separatist forces by giving an outlet to legitimate demands for Britain's nations to govern their own affairs.

But with a Scottish National Party executive governing at Holyrood and Plaid Cymru in coalition with Labour in Cardiff, a large majority of peers quizzed for the poll said they believed the opposite outcome had resulted.

Some 60% of a "peers panel" questioned by Dods Polling said that establishing the devolved institutions had boosted nationalism slightly, and a further 20% said it had done so greatly.

Among those who felt nationalism had been fuelled by devolution were 75% of Labour peers and 50% of Liberal Democrats - the two parties which pushed through the legislation.

The level of concern about the impact of devolution was one of the most eye-catching findings from the first ever Dods peers panel, published on the website epolitix.com.

Other findings included 59% support among peers for a selective amnesty allowing illegal immigrants to earn British citizenship and stay in the UK. Just over one-third of members of the second chamber (35%) said no such amnesty should be granted.

Around half (51%) agreed that the Government should make new laws that would require supermarkets to price alcohol "responsibly", against 34% who said it should not.

And a majority (57%) backed Chancellor Alistair Darling's decision announced last year to tax non-domiciled residents £30,000 per year, against 34% who opposed it.