The official Vote Leave campaign group appears to have added fake sound effects of blood-curdling screams and smashing glass to footage of a brawl in the Turkish parliament that it used to warn of the prospect of Turkey joining the EU.

A comparison of the Vote Leave broadcast with the original footage by The Independent indicates that the audio track was doctored.

At one point in the video a woman’s scream can be heard, which does not occur in the raw footage.

The scream appears to be a stock sound effect used by filmmakers, which is available on YouTube under the title: ‘Scream 6: woman medium perspective panicked shrieks of fear’.

Later in the video, the sound of smashing glass appears to have been added to footage of an individual throwing an object during the fight, which took place in a committee of the Turkish parliament.

Another scream of pain – again, not audible in the original footage – appears to have been added to suggest someone being struck and injured by the object.

You can hear the inserted scream and sound of smashing glass in the video at the top of this article.

Vote Leave have declined to comment to The Independent.

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The campaign group, which is spearheaded by Boris Johnson and Michael Gove, faced criticism when it first broadcast the video, on the same day that Mr Gove warned that if Turkey’s joined the EU it could contribute to a UK population explosion of 5.23 million by 2030.

At the time, the Liberal Democrats called the video, which appears calculated to highlight the violence and aggression of the scene in the Turkish parliament, “xenophobic” and “from the propaganda playbooks of 100 years ago”.

The official Remain campaign criticised what they said now appeared to be a deliberate attempt to dramatise the footage and accused Vote Leave on indulging in "post-truth politics".

James McGrory, chief campaign spokesman for Britain Stronger in Europe, told The Independent: “Not content with telling porkies about Turkey joining the EU – when even Boris Johnson says it’s “not on the cards” – it seems Vote Leave have been reduced to making fake videos too.

“This is entirely in keeping with the character of their campaign. Their argument is based on three big lies – Turkish accession, our contribution to the EU budget, and an EU army – which have repeatedly been shown to be untrue.

“This Thursday, the British people can take the irreversible step of leaving the EU based on the lies of a campaign steeped in post-truth politics. Or they can vote for more jobs, lower prices, and a decent, tolerant Britain that works together with Europe.”

The Leave campaign has warned repeatedly that Turkey is on the brink of joining the EU. While Turkish accession is a long-term goal in both Brussels and Ankara, and is backed in principle by the British government, Turkey has met conditions of entry in only one of 35 key policy areas. Each EU member state also has a veto over its accession, and tensions between Turkey and EU member Cyprus mean that it joining the EU remains a distant prospect.

The fight in the Turkish parliament featured in the Vote Leave video took place early in May between members of the ruling AK Party and the pro-Kurdish opposition, over proposals to strip parliamentarians of their immunity from prosecution.

Opposition MPs viewed the bill, which was eventually passed, as a vehicle for the government to expel rival MPs. Vote Leave have declined to explain why it used the footage in a campaign video about the UK’s EU membership.

Britain votes in the EU referendum on Thursday, in a febrile atmosphere in which Leave campaigners have been accused of stoking up anti-migrant and anti-refugee feeling.

Former Conservative cabinet minister Baroness Warsi became the latest high-profile figure so far to defect from the Leave campaign, accusing it of “hate and xenophobia”.

Singling out the Justice Secretary, she said Mr Gove had lied about the prospect of Turkey joining the EU.

“Why is it people like me, instinctively Eurosceptic who feel the EU needs reform ... feel they now have to leave leave?” she said on BBC Radio 4’s Today programme “Because day after day what are we hearing? The refugees are coming, the rapists are coming, the Turks are coming.”

Later, she compared Mr Gove to far-right politicians Geert WIlders, Marine Le Pen and the BNP.

Baroness Warsi also branded Nigel Farage's controversial anti-migrant "Breaking Point" poster, which depicted refugees and migrants on the borders of Slovenia, as indefensible.

She said the poster was “perpetuating a set of lies about who those people are, where they were going, suggesting they were coming to the United Kingdom”.

“This kind of nudge-nudge, wink-wink xenophobic racist campaign may be politically savvy or useful in the short term but it causes long-term damage to communities,” she told the BBC.

Mr Farage was forced to defend the poster from attacks from his own side, with Mr Gove saying he "shuddered" when he saw it.