Boris Johnson was heckled in Newcastle as he attacked David Cameron for "shamefully" spending £9.3 million of taxpayers' money on a pro-EU leaflet.
The London mayor criticised the "scared" tactics of the remain campaign as he continued his northern "Brexit blitz" tour.
But Boris had the start of his speech interrupted, with hecklers shouting "no Tories in Newcastle".
A group of women were escorted from the building.
Boris Johnson has criticised Barack Obama who plans to urge the UK to remain in the EU referendum branding it "hypocritical".
The EU referendum campaign has officially begun - ten weeks before Britain decides whether to leave the union.