Government claims that the UK’s carbon dioxide output has dropped by more than a 10th since 1990 might not be true if greenhouse gas emissions from shipping are included, an influential group of MPs will say on Monday.

The environmental audit committee, in a report on shipping emissions, said it was not possible to gauge the full extent of emissions from shipping as they were not counted towards the UK’s targets under the Kyoto protocol and were not covered by the European Union’s emissions trading scheme.