Britain is considering issuing billions of pounds of extra government debt to create a new state-backed infrastructure investment fund that could help finance the country's future pension liabilities, the Sunday Times newspaper reported.

A Treasury spokeswoman declined to comment on the specific proposal, but said that a range of ideas was under consideration in the run-up to Conservative finance minister George Osborne's November 29 autumn statement.

Osborne is under pressure to come up with measures to boost British economic growth at a time when Bank of England officials have warned the country risks slipping back into recession, even with a second round of quantitative easing.

Some 100 economists wrote in a letter to the Observer newspaper on Sunday that Osborne should rein back the deficit-cutting plans that form the centrepiece of the Conservative-Liberal Democrat coalition's economic policy.

The opposition Labour Party's finance spokesman, Ed Balls -- who has long called for slower deficit reduction -- also made this point again in a statement to media late on Saturday.

The Sunday Times said that the financier and Conservative Party donor Eddie Truell had proposed a fund worth hundreds of billions of pounds that would invest in projects such as roads, power stations and affordable housing.

The proceeds would be ring-fenced to pay for future public sector pensions, which currently have a deficit of around 1.3 trillion pounds.

These liabilities are already factored into ratings agencies' assessment of Britain's creditworthiness, even though they are not fully factored into the country's public accounts, so in theory issuing gilts to fund them should not affect Britain's credit rating, the paper said.

However, ratings agencies have also placed a lot of weight on the government's commitment to start reducing debt as a share of GDP by the end of the parliament, and it is unclear how they would view such an infrastructure scheme.

Separately, the Sunday Telegraph reported the Treasury had been in contact with the London Stock Exchange to look at how to make it easier for small savers to buy corporate bonds, which usually require very high minimum investments.

At the Conservative Party's annual conference at the start of the month, Osborne promised to announce 'credit easing' measures to improve businesses' access to finance in his autumn statement next month.

(Reporting by David Milliken; Editing by Helen Massy-Beresford)