Three new national parks would be created in England under the Liberal Democrats, the party has announced.

The election manifesto pledge would take the country’s number of national parks up to 13.

The Chilterns in Hertfordshire and Buckinghamshire – along with the Mendips, Cotswolds and Quantocks – have been named as possible locations for the parks.

The party said it would maintain the new and existing parks with an annual spending commitment of £50m.

England currently has 10 national parks, including Dartmoor, Exmoor and the Lake District.

The Surrey Hills, Northumberland coast and Dorset are also being mooted as potential locations for the new parks.

Liberal Democrat leader Sir Ed Davey said the party wanted to create new parks and ensure “our existing parks, beloved by people across the country, are protected for generations to come.”

Sir Ed said it was “hard to overstate” the difference green spaces can make to communities.

The party said it would also plant 60 million trees a year.

Sir Ed took aim at the Conservatives for “failing” to deliver on their 2019 manifesto commitment to create one new national park.

The government last year did ask Natural England to consider a list of possible sites for a new park, which could include the Chilterns, the Cotswolds and Dorset, but the process can take up to five years.

At the time Environment Secretary Steve Barclay described national parks as “a really important part of our way of life”.

Labour has pledged to plant three new national forests and stop the use of bee-harming pesticides if it forms the next government, under a “countryside protection plan” announced on Friday.