Royal Bank of Scotland's chairman, Sir Tom McKillop, claimed this week that an attempt by environmental activists to hold it responsible for the carbon emissions of oil and gas projects which it finances was "deeply, deeply flawed".

London-based Platform, which describes itself as a campaigner "for social and ecological justice", claimed in a recent report backed by Friends of the Earth Scotland that Royal was responsible for carbon emissions greater than those of all of Scotland.

McKillop rounded on Royal's critics as the bank published its 2006 Corporate Responsibility Report. Unveiling this report, Royal declared: "As a responsible business, we recognise the significant global threat posed by climate change and take a proactive role to ensure we make a difference where we can."

The report highlights Royal's purchases of electricity from renewable sources. The bank also points to £55m of investment in its property portfolio, including implementation of energy-saving measures such as insulation and piloting of solar roof tiles and biomass boilers.

When it was put to him by The Herald that Royal's consideration of its carbon footprint appeared to focus on internal matters, and asked whether he viewed criticism of the impact of its financing of oil and gas projects as overblown, McKillop highlighted the bank's position as the world's largest arranger of finance for renewable energy schemes. Royal noted it had committed $2.6bn of funding to such renewable schemes last year - the same amount as it had provided for oil and gas infrastructure projects.

McKillop said: "There has been one particular report which accused us almost of being responsible for some of the carbon emission issues that are around through our financing activities in the energy sector."

He claimed that this Platform report was, on an economic and social basis, "deeply, deeply flawed".

McKillop said the report implied "banks should be responsible for the carbon footprints of everyone they lend to".

He added: "That would mean banks would be responsible pretty much for the carbon emissions of the world."

"It is just completely flawed," he claimed, saying that the argument could be extended to take in the impact of households' carbon emissions if Royal provided a mortgage, or the environmental impact of cars if it had provided motor finance.

Platform claimed Royal was, in 2005, responsible for about 37 million tonnes of carbon emissions, more than one hundred times the level the bank had reported for that year.

On a separate matter, albeit another with an environmental slant, McKillop made plain his opinion that the size of Royal's annual report was "ludicrous". Royal's 2006 annual report runs to more than 260 pages.

However, making it plain this was not by choice and highlighting international regulatory requirements, McKillop added: "The problem is driven (by) the demands of regulatory bodies. I think the direction we have gone in is a bit ludicrous, but it is sadly where we are driven."

McKillop, however, reserved particular scorn for form 20-F, required by US regulators.

He said this involved "horrendous box-ticking and accounting for anything that could move in any direction".

In its Corporate Responsibility Report, Royal says it last year recorded its largest-ever figure for lending to small businesses and social enterprises in the UK's most deprived areas - £677m.

It declares that it led the banking sector with a commitment to install 300 free-to-use cash machines in rural and deprived areas, and says it will put in a further 200 this year. Royal also highlights its efforts to educate children and adults about personal finances and flags its achievement of a 14% reduction in internet fraud, in contrast to an industry-wide increase of 46%.