Investigation follows revelations of Lynton Crosby firm running ad campaign calling voters to lobby MPs.

A series of hugely influential Facebook advertising campaigns that appear to be separate grassroots movements for a no-deal Brexit are secretly overseen by employees of Sir Lynton Crosby’s lobbying company and a former adviser to Boris Johnson, documents seen by the Guardian reveal.

The single biggest known British political advertiser on Facebook is a mysterious pro-Brexit campaign group pushing for a no-deal exit from the EU. The revelation about Britain’s Future, which has never disclosed the source of its funding or organisational structure, has raised concerns about the influence of “dark money” in British politics.

Britain’s Future has spent £88,000 on pro-Brexit ads despite Facebook transparency promises.