Demonstrators retreated from an Istanbul protest square Wednesday after a night of running battles with riot police as Turkish Prime Minister Recep Tayyip Erdogan moved to crush mass demos against his Islamic-rooted government.

By midday, hundreds of officers armed with riot shields and backed by water cannon trucks lined up along the eastern side of the square. Just a stone's throw away, weary demonstrators huddled up in Gezi Park.

Small crowds, mainly commuters and curious passers-by, milled around the area after a large clean-up operation removed all evidence of the unrest, clearing the square of stray tear gas canisters, anti-Erdogan banners and makeshift barricades.

The premier was to hold talks with some protest leaders on Wednesday, but many protesters said the unexpected crackdown on Taksim Square, which had seen no police presence since June 1, had made them lose faith in any dialogue.

"We don't accept it," said Anessa, a 29-year-old photographer, complaining that the government had cherry-picked the groups invited to the meeting.

Walking around a subdued Gezi Park in the rain, she said the violence only made protesters more determined. "We are not afraid. We are very angry and we will not stop."

The nationwide unrest first erupted after police cracked down heavily on May 31 on a campaign to save the park from redevelopment, spiralling into mass displays of anger against Erdogan.

Four people, including a policeman, have died in the unrest. Nearly 5,000 demonstrators have been injured, tarnishing Turkey's image as a model of Islamic democracy.

Erdogan, seen as increasingly authoritarian, has taken a tough line on the demonstrators, many of whom are young and middle-class. On Tuesday, he warned his patience had run out.

"We won't show any more tolerance," he told cheering lawmakers of his Justice and Development Party (AKP) in a speech broadcast live on television.

Hours later, Taksim Square resembled a battle scene, police firing volleys of tear gas to disperse tens of thousands chanting "Erdogan, resign!" and "Resistance!"

Cat-and-mouse games continued into the night, with police firing gas, jets of water and rubber bullets at demonstrators who hurled back fireworks, bottles and molotov cocktails.

The capital Ankara also saw renewed clashes overnight as riot police used gas, pepper spray and water cannon against thousands of protesters near the US embassy. Some threw rocks in response.

-- 'Democratic maturity' --

While expectations were low for a quick resolution to the conflict, President Abdullah Gul on Wednesday said Erdogan's meeting with demonstrators was a sign of the country's "democratic maturity".

"People take to the streets here like in the most developed countries in Europe," he said, adding that he was confident Turkey would "overcome the trouble".

Police did not intervene in Gezi Park overnight, where volunteers offered first aid to victims of the clashes, though many protesters abandoned their tents to escape wafts of tear gas drifting in from Taksim.

"This was one of the biggest events in Turkey," law student Fulya Dagli, 21, said about the overnight clashes as she handed out breakfast in the park.

"People are learning not to be scared of the government. That's something we gained and can't give up again."

In a clear sign that police had reclaimed Taksim Square, they unfurled two massive Turkish flags from a nearby building, as well as a large portrait of Mustafa Kemal Ataturk, the father of modern Turkey, whose image has also been adopted by the protesters.

Confident in his enduring popularity, Erdogan, in power since 2002, has urged loyalists to respond to the demonstrators by voting for the AKP in local polls next year.

His AKP has won three elections in a row and took nearly half the vote in 2011, having presided over strong economic growth.

The first campaign rallies will be staged in Ankara and Istanbul this weekend and are expected to gather tens of thousands of party faithful.

Turkey, a country of 76 million at the crossroads of East and West, is a key strategic partner in the region for the United States and other Western allies. Many of them have criticised Erdogan's handling of the crisis.

German Foreign Minister Guido Westerwelle on Wednesday said the images of demonstrators being chased down by riot police were "disturbing".

"The Turkish government is sending the wrong message to the country and to Europe," he said, adding that Ankara must do "all in its power" to protect democratic rights.

Italy's Foreign Minister Emma Bonino said the unrest was "the first serious test" for Turkey in its long-time bid to join the European Union.