The government moved to tighten its climate change bill still further last night, tabling amendments designed to extend the reach of the feed-in tariff and limit the extent to which carbon credits from overseas can be used to count towards UK emission targets. The bill is now expected to receive its final vote this week and is on track to receive Royal Assent on 27 November, making the UK the first country to feature legally binding emission reduction targets on the statute book.

Green groups had expressed fears the bill - which includes a recently upgraded target to cut emissions by 80 per cent by 2050 and incorporate aviation and shipping - would allow successive governments to meet the targets by buying large numbers of carbon offset credits from projects in the developing world, rather than focusing on action within the UK.

A number of peers, including Labour lords Whitty and Puttnam, and both opposition spokesmen on energy and climate change Lords Taylor of Holbeach and Lord Teverson, raised concerns about the role imported credits could play.

In a letter to a newspaper yesterday they warned: 'Relying sufficiently on emission reductions which take place overseas could influence long-term investment decisions here in the UK, particularly in the power sector, locking the country into high carbon economy for years to come, when the overwhelming need is to tackle climate change, develop clean technologies and benefit from the growth in green jobs.'