'We have not responded to punches with punches. From now on security forces will respond differently,' Erdoğan says

Turkey's prime minister defied a growing wave of international criticism on Wednesday and issued a chilling warning to the protesters who have captured central Istanbul for a fortnight, declaring that the demonstrations against his rule would be over within 24 hours.

Recep Tayyip Erdoğan's ultimatum, which he said was conveyed to his police chief and interior minister, ratcheted up the tension in Turkey after a relatively calm day following the mass teargas attacks by riot police in Istanbul city centre on Tuesday evening.

"We have not responded to punches with punches. From now on security forces will respond differently," Erdoğan said after meeting a team said to be representing the protesters for the first time. "This issue will be over in 24 hours."

The sense of a looming denouement at Gezi Park off Taksim Square in central Istanbul was reinforced when a deputy leader of Erdoğan's ruling Justice and Development party (AKP) said the park had to be cleared of demonstrators as soon as possible.

Thousands of protesters again gathered at the park yesterday, with phalanxes of riot police marshalling nearby.

The sense of a final showdown was reinforced by Istanbul's governor, Hüseyin Avni Mutlu, who ordered the protesters to clear the park for their own "safety".

"Families should take their children out of there," he warned.

But the ruling party's deputy chairman and government Hüseyin Çelik said that a city-wide referendum could be held on the initial issue that sparked the wave of national protest – whether the park should be demolished to make way for a shopping mall and a replica of an old military barracks.

And Erdoğan's belligerent statement contrasted with more conciliatory language from President Abdullah Gül, who urged dialogue with legitimate peaceful protesters, the vast majority of the tens of thousands who have taken to the streets over the past two weeks.

Protest leaders in the park pledged to stay put as around 1,000 lawyers also took to the streets in an unusual escalation of the demonstrations to complain about the detention of 45 of their colleagues on Tuesday and to voice solidarity with the "resistance".

The prime minister also held talks over the protests in Ankara, but it was unclear whether those he was talking to represented the demonstrators. Activist Tekin Deniz said: "This delegation is made up by the prime minister, it does not represent any of us. These meetings are a joke."

The umbrella group behind the protest uniting dozens of trade and professional associations, Taksim Solidarity, denounced the Ankara talks as illegitimate. "No meeting, while the police violence disregarding right to life so relentlessly continues in and around the Gezi Park, will produce results," it said. "We are waiting for you in Gezi Park. We are here and we are not leaving."

In the strongest criticism yet of Erdoğan's hard line, the European Union contradicted the prime minister and voiced support for the protesters, saying they had been largely peaceful and subject to indiscriminate violence from riot police. It demanded an investigation of the extreme reaction, and called on Erdogan to cancel big rallies of his Justice and Development party (AKP) scheduled for the coming weekend.

"There is a real polarisation of opinion. Major AKP rallies in Istanbul and Ankara this weekend would risk adding to the tension when we need to see a de-escalation," said Catherine Ashton, the EU's foreign policy chief.

Guido Westerwelle, the German foreign minister, added: "We expect Prime Minister Erdoğan to de-escalate the situation and to seek a constructive exchange and peaceful dialogue."