Green Party co-leader Caroline Lucas has accused her rivals of a “scandalous” failure to put forward ideas for protecting the environment.
She claimed Brexit could see the environment “trashed” and yet it had not been reflected in party manifestos.
The Conservatives have promised to produce a 25-year plan which would ensure they leave the environment in a better condition.
Labour has pledged to retain existing EU environmental protections.
Speaking at a rally of supporters on Parliament Square, Ms Lucas said: “The environment has been conspicuous by its absence so far in this election campaign – there is nothing from the other parties.”
She told the BBC it was “scandalous that the environment has been absolutely missing in the campaign so far”.
Ms Lucas has also sent letters to Theresa May and Labour leader Jeremy Corbyn expressing her “alarm” at what she sees as their neglect of this area.
She accuses Labour of “failing on a number of key issues” such as fossil fuels and airport expansion.
The Labour manifesto backs airport expansion as long as it meets climate change obligations.