The prime minister says the target of reducing the UK's greenhouse gas emissions to "net zero" by 2050 will need work "across the whole breadth of society" to achieve.

"Net zero" means emissions from homes, transport, farming and industry will have to be avoided completely or - in the most difficult examples - offset by planting trees or sucking CO2 out of the atmosphere.

She said introducing legislation for the plan would put the UK on track to be the first major economy to put such a commitment into law.

She added that she believes it is possible to lower emissions and still have economic growth.