Image caption More than 300,000 renewable energy jobs would be created under Mr Corbyn's plans

A future Labour government would challenge the dominance of the "big six" energy firms by championing more than 1,000 publicly-owned local energy providers, Jeremy Corbyn will say.

The new not-for-profit co-operatives would focus on renewables and have a "right to supply" energy directly.

In a speech on Wednesday, Mr Corbyn will also call for an end to fracking.

Labour leadership challenger Owen Smith said Mr Corbyn's previous actions meant he lacked credibility on green issues.

The result of the Labour leadership election will be announced on 24 September.

Launching his environmental manifesto, Mr Corbyn will say he is putting "new energy economics" at the heart of his plans to curb rising bills and tackle climate change.

If elected prime minister, he will commit to:

Promoting 200 new publicly owned "local energy companies" by 2025 able to supply towns and cities across the UK

Encouraging 1,000 new "community energy co-operatives", backed by state funding to pay for connection to the National Grid

Insulating four million homes to high energy efficiency standards

Phasing out coal-fired power stations by the early 2020s

Restoring the Climate Change Department

Supporting plans to plant 64 million trees in next 10 years

In his speech, Mr Corbyn will say he wants 65% of the UK's electricity to come from renewable sources by 2030, making Britain the world's leading producer.

"To achieve this we will accelerate the transition to a low-carbon economy, and drive the expansion of the green industries and jobs of the future, using our National Investment Bank to invest in public and community-owned renewable energy," he will say.

"This will deliver clean energy and curb energy bill rises for households; an energy policy for the 60 million, not the big six energy companies."

'Social justice'

Mr Corbyn has previously floated the idea of bringing the UK's largest energy providers back into public ownership but he will say his focus is on tightening regulation and giving consumers alternative sources of affordable energy.

Making clear his opposition to fracking, he will say shale gas extraction - which has been licensed on a limited basis in the UK - is "not compatible" with tackling climate change and could potentially breach the UK's obligations under the Climate Change Act, which mandates emissions cuts of 80% by 2050.

"We will act to protect the future of our planet, with social justice at the heart of our environment policies" he will add.

Image copyright PA Image caption Mr Corbyn says coal-fired power stations should be phased out by the early 2020

Mr Smith said that by failing to campaign effectively for Britain to remain in the EU, Mr Corbyn had put vital environmental protections at further risk.

"It's impossible for Jeremy Corbyn to speak with credibility on environmental policy," a spokesman for Mr Smith said.

"He has called for the reintroduction of deeply damaging open-cast coal mining and only had one meeting with his shadow environment team in nine months as leader."

In a Commons debate on Wednesday, Labour will press the government to ratify last year's Paris Climate Agreement immediately - which it says would put the UK in the vanguard of international steps to cap increases in temperatures.

The government is in danger of missing its target of sourcing 15% of the UK's energy from renewables by 2020 but says it is still committed to it.