The government will face mounting pressure to impose tougher carbon emissions limits after failing to do so in the Climate Change Bill's second Commons reading.

Environment minister Phil Woolas this week outlined the government's response to amendments made in the House of Lords. As it stands, the bill sets a target to reduce UK carbon emissions by at least 60 per cent by 2050. But more than two-thirds of Labour backbenchers are among 257 MPs who have signed an early day motion for an 80 per cent cut. They also want the bill to cover international aviation and shipping emissions. Friends of the Earth parliamentary campaigner Martyn Williams added that ministers are ignoring scientists' advice.

The government has admitted that the 60 per cent figure is outdated and asked its climate change committee to consider raising it, although its advice is not binding. Ministers agreed to report back to parliament on whether the UK's share of aviation and shipping emissions should be included in the bill within the next five years.

Meanwhile, the government has delayed a crucial vote on the Planning Bill as it seeks to persuade MPs to back plans for an infrastructure planning commission. It followed signals that Labour MPs are set to rebel.

A DCLG spokesman said the vote is now likely to take place in the week beginning 23 June.