Politicians on rival sides of Britain's referendum on membership of the European Union clashed in a debate broadcast online Tuesday, as expectations of an increasingly likely Brexit roiled global markets.
Stock markets extended a global sell-off after polls indicated increasing support for an exit from the 28-member bloc on June 23, while the top-selling Sun tabloid added to a sense of momentum by endorsing "Leave".
In a debate live-streamed on YouTube, politicians campaigning for a so-called Brexit dismissed fears of damage to Britain's economy by arguing EU regulations were holding it back.
"The whole European project is a machine for generating excessive bureaucracy and red tape," said Boris Johnson, a Conservative former London mayor and leading pro-Brexit campaigner.
"It is an economic disaster area."
Alex Salmond, the former Scottish National Party leader who is campaigning to remain, countered that the EU brought social and worker protections and allowed Britain access a trade market of 500 million people.
The bloc had brought "peace and stability" to Europe, he said.
The endorsement by The Sun, owned by Rupert Murdoch, thrilled UK Independence Party (UKIP) leader Nigel Farage who brandished a copy of the newspaper while out campaigning.
In a front page editorial, the paper urged its 4.5 million readers to "BeLEAVE in Britain", saying: "We must set ourselves free from dictatorial Brussels."
It warned that staying in the EU would leave Britain "powerless" to stop the hundreds of thousands of European migrants who come to the country every year, putting "catastrophic pressure" on public services.
Investors have responded to the pro-Brexit momentum by selling stocks and putting their money in safe investments, with Europe's main markets down sharply and the euro hitting a 3.5-year low.
For the first time, demand for German government bonds viewed as rock-solid investments pushed their yields into negative territory.
- Blunt tactics -
The online debate was marked by a tense exchange over immigration, which has been a driving factor behind support for leaving the EU and a hot political issue in Britain for years.
Salmond said he was "fed up" with immigrants being portrayed negatively in the campaign, while Johnson insisted that immigration depressed wages.
But there were signs that the pro-EU side felt voter concerns had to be addressed as the deputy leader of the pro-remain Labour party, Tom Watson, said the EU's free movement rules might need to be reviewed.
"Woe betide politicians that don't listen to what voters tell them," he told the BBC.
"I think we have to reassure people that if they vote Remain on Thursday June 23, that isn't the end of the reform package for Europe. You know, I think a future Europe will have to look at things like the free movement of labour rules."
Allowing workers to move freely between the EU's member states is a fundamental principle of the bloc.
Polls in recent weeks have shown an uptick in support for the pro-Brexit campaign.
A YouGov poll for The Times gave the "Leave" camp 46 percent, compared to 39 percent for "Remain" -- the fourth survey since Friday to put them ahead. Only one has put the Brexit camp behind.
A compilation of the six latest polls by the WhatUKThinks research project, which excludes undecided voters, puts "Leave" ahead by 51 percent to 49 percent.
Matt Singh, a polling expert who runs the Number Cruncher Politics website, told AFP: "In terms of the direction of travel, there's clear evidence of a move towards 'Leave'."
But he cautioned that there were still questions about the extent of the move. On Monday, Singh put the probability of a Brexit at 33 percent, its highest-ever level.
As the referendum nears, campaigners are pushing for a high turnout -- using increasingly blunt tactics.
The "Remain" camp published a letter from 60 health experts warning that Brexit would imperil the state-run National Health Service.
Meanwhile Labour leader Jeremy Corbyn announced that workers' rights such as holidays and maternity leave would be at risk in an intervention flanked by party members and trade union leaders.
Hollywood actress Keira Knightley, who has previously expressed support for "Remain", made a short film in which she said it took only five seconds for her to practise the "perfect awards face".
"And it takes five seconds to mark an X in a ballot box. Five seconds to stop others fucking with your future," said the Briton.