A wave of demonstrations have broken out up and down the UK to protest the narrow result of the referendum that seems set to take Britain out of the European Union. Crowds have gathered in Edinburgh, Glasgow, London and elsewhere, hitting out at what they have described as the "racist" and "anti-immigrant" tone taken by the leave campaign and its supporters.

A hastily-organised demonstration in Parliament Square took place on Saturday afternoon, attracting hundreds of young people, whose demographic voted overwhelmingly to stick with Europe in Thursday's poll. It was coordinated through Facebook by the journalist and presenter Bille JD Porter, who told the BBC that she believed her generation was disillusioned by the whole referendum campaign, and that the leave camp had "fostered a really ugly side of people".

"Politicians are shouting and ramming statistics down people's throats," she said. "It has divided the country and had people booing and hissing at each other."

On Friday night, an imprompu march also held in London crossed London Bridge and ended up at the offices of The Sun newspaper near the Shard, to protest the role it played during the campaign. An estimated 650 people made the trek, chanting "refugees are welcome". The Sun shares the building with the Times, which supported remaining in the EU, which is in Southwark, a district which voted to remain.

Meanwhile, in Edinburgh, a large crowd gathered at Holyrood, the Scottish Parliament building, at a rally organised under the message: "After the Referendum, Defend all Migrants". A similar demonstration was held in the centre of Glasgow.

Organisers said: "The EU referendum has unleashed a torrent of racism. Unabashed, unchecked racist and xenophobic hyperbole has dominated the entire campaign, with migration being defined as a 'problem', or 'crisis', with bigotry being stoked up against migrants, and with EU citizens living here being systematically denied a voice."

A protest has also been organised in York for Saturday 2 July, where voters elected to remain despite the surrounding areas voting no. Sally Sadik, who has organised the event, said: "We have been lucky to receive so much talent and culture from immigration. They are the backbone of this country and work so hard to contribute to a society that wrongly accuses them of destroying British opportunities, rather than the actual perpetrators from government elite. This decision would be irreversible, and destroy so much of what I thought this country stood for."