ISTANBUL (AFP) - Riot police fired tear gas and rubber bullets to clear protesters from an Istanbul square on Tuesday as Turkish Prime Minister Recep Tayyip Erdogan warned he would show "no more tolerance" for the unrelenting mass demonstrations against his Islamic-rooted government.

Hundreds of police stormed the city's Taksim Square, the epicentre of nearly two weeks of unrest, in the early morning and brought bulldozers to clear the makeshift barriers erected by demonstrators after police pulled out of the area on June 1.

The police action surprised protesters, many of whom were dozing in nearby Gezi Park, because it came just hours after Erdogan agreed to hold talks with protest leaders on Wednesday, his first major concession since the trouble began.

But the premier made no mention of the olive branch on Tuesday and resumed his tough stance against the demonstrators who have thrown up the biggest challenge yet to his decade-long rule.

"This episode is now over. We won't show any more tolerance," the premier told cheering lawmakers of his Justice and Development Party (AKP) in a speech broadcast live on television.

Acrid smoke filled Taksim Square as police doused protesters with tear gas and jets of waters. Some demonstrators, in helmets and gas masks, responded with molotov cocktails, fireworks and stones.

"Can you believe that? They attack Taksim, gas us in the morning just after proposing talks with us? What kind of leader is that?" said Yulmiz, 23, after waking up to the clashes in his tent in Gezi Park.

"We won't abandon Gezi," he vowed. "I am not afraid of their water cannon, it'll be my first shower in three days."

The nationwide unrest first erupted after police cracked down heavily on May 31 on a campaign to save Gezi Park from redevelopment.

The trouble spiralled into mass displays of anger against Erdogan, who is seen as increasingly authoritarian, tarnishing Turkey's image as a model of Islamic democracy.

Erdogan said on Tuesday that four people, including a policeman, had died.

Nearly 5,000 people have been injured.

In a rousing speech to lawmakers, Erdogan urged "sincere" protesters in Gezi Park to pull back, warning that their environmental campaign was being hijacked by "an illegal uprising against the rule of democracy".

By late afternoon, clashes were still raging in the square between police and protesters who were chanting "Resistance!", while nearby Gezi Park remained peaceful.

In a symbolic gesture, police removed anti-Erdogan banners from a building overlooking Taksim and replaced them with a single Turkish flag and a large portrait of Mustafa Kemal Ataturk, the father of modern Turkey, whose image has also been adopted by the protesters.

Istanbul governor Huseyin Avni Mutlu sought to justify the police intervention, saying the protesters' takeover of Taksim Square "tarnished the country's image before the eyes of the world" and assured demonstrators police would not storm Gezi Park.

But under the park's sycamore trees, tension was mounting.

"If they chase us out, we will be back," vowed pensioner Ali, 63, a surgical mask covering his mouth.