Turkey has threatened to rip-up its migrant deal with the EU claiming it will stop letting migrants across its border unless Brussels implements a pledge to grant Turks visa-free travel.

President Recep Tayyip Erdogan warned the European Union that it needs Turkey 'more than we need you' as tensions grew over promises for visa liberalisation in a crucial deal on stemming the flow of migrants to Europe.

Turkish Prime Minister Ahmet Davutoglu had earlier bluntly told the EU that Ankara would no longer abide by the March migrant accord if Brussels fails to implement the visa-free travel by June.

Turkey's President Recep Tayyip Erdogan (above) warned the EU that it needs Turkey 'more than we need you' as tensions grew over promises for visa liberalisation in a crucial deal on stemming the flow of migrants

Critics are now concerned that the EU appears ready to give in to pressure laid on by the country.

UKIP MEP James Carver, a member of the European Parliament's foreign affairs committee, told the Daily Express: 'The EU wants to give visa-free travel to all Turkish citizens by June, and eventually full Turkish accession. British people are appalled that the EU is giving into blackmail and allowing visa-free travel.

'This shows that the Brexit debate is not really about where the EU is now but the direction and destiny it is travelling to in the future. Turkey is too big, too poor and too different from us.

'I certainly don't wish to be in a political union with a country with such a despicable human rights record, which massacres the Kurds and helps out Islamic State in an underhand way too.'

Tensions have also been fuelled by a European Parliament report published last week that accused Turkey of backsliding on democracy and pressure from Ankara on Berlin to prosecute a German comic over a poem satirising Erdogan.

The issues are coming to a head as Chancellor Angela Merkel and top EU officials prepare to travel to the Turkish city of Gaziantep, close to the Syrian border, on Saturday to discuss implementation of the migrant deal.

'The European Union needs Turkey more than Turkey needs the European Union,' Erdogan said to cheers in a televised speech to municipal leaders in Ankara.

Kilis, a city located just 10km from the Syrian border and the location of the Oncupinar Border crossing, has been Turkey's frontline during the refugee crisis. The country has taken around three million people from Syria

Denouncing a European Parliament report as 'provocative', he criticised it for praising Turkey's work in hosting some 2.7 million refugees from the war in neighbouring Syria.

'Three million people have been looked after in this country so they don't disturb the Europeans. Is there anything about this in the report?' said Erdogan.

'At a time when our relations with the European Union are in a positive phase regarding the migrants... it is provocative to come out with a report like that.'

Turkey has been given a string of promises from the European Union - including visa-free travel to the border-free Schengen Zone and a new momentum for its long-stalled membership bid - in return for stepping up efforts to stop migrants crossing to EU territory.

'This is a mutual commitment,' Davutoglu said earlier this week of the promise to exempt Turks from visas by the end of June.

'If the EU cannot take the necessary steps required of it then of course it cannot be expected of Turkey to take these steps.'

If the June deadline is not adhered to, 'of course no-one can expect Turkey to adhere to its commitments,' he added.

Marc Pierini, visiting scholar at Carnegie Europe, said that Ankara was 'very keen' to obtain the visa-free regime but was also aware there were are 72 technical conditions to be fulfilled.

'As of today, these conditions have not been met yet,' he said.

Once they are met, the issue will be put to EU interior ministers for a qualified majority vote in June.

'Turkey does not have the ability to change the voting procedures in EU Ministerial Councils,' Pierini commented.

UKIP MEP James Carver (pictured), a member of the European Parliament's foreign affairs committee, said of Turkey's threat: 'British people are appalled that the EU is giving into blackmail and allowing visa-free travel'

EU Commission chief Jean-Claude Juncker also warned Ankara that the 'criteria (on visa liberalisation) will not be watered down in the case of Turkey'.

He said Davutoglu had raised the issue in talks in Strasbourg 'but he did not need to because... I have made clear that this will be done when Turkey has fulfilled all the conditions, which it is in the process of doing.'

He added: 'We concluded an accord and this deal is being applied. There is no need to make any kind of threat.'

The March 18 accord sets out measures for reducing Europe's worst migration crisis since the Second World War, including stepped-up checks by Turkey and the shipping back to Turkish territory of migrants who land on the Greek islands.

But the prospect of visa-free travel for Turks has been hugely controversial in some EU countries, where leaders have been accused of bending over to fulfil Erdogan's demands at a time when he is accused of growing authoritarianism.

In his address to the PACE, Davutoglu did not emphasise the visa issue but lamented the lack of foreign assistance given to Turkey for the Syrian refugees, saying this amounted to just $500 million (440 million euros) compared to Turkey's spending of $10 billion.