Thousands of Turks dug in on Saturday for a weekend of anti-government demonstrations despite Prime Minister Recep Tayyip Erdogan's demand for an immediate end to the worst political unrest of his decade in power.

In central Istanbul's Taksim Square, where riot police backed by helicopters and armored vehicles clashed with protesters a week ago, activists spent the night in a makeshift protest camp, sleeping in tents and vandalized buses, or wrapped in blankets under plane trees.

What began as a campaign against the redevelopment of Gezi Park in a corner of Taksim Square spiraled into an unprecedented display of public anger over the perceived authoritarianism of Erdogan and his Islamist-rooted AK Party.

Police firing tear gas and water cannon have clashed with groups of protesters night after night in Istanbul, Ankara and other cities across the country for much of the past week, leaving three dead and some 4,000 injured.

Erdogan demanded on Friday an immediate end to the protests, saying they had been founded on a "campaign of lies." He has branded the demonstrators as looters and has said the protests are being manipulated by "terrorist" groups.

Erdogan gave no indication of any immediate plans to remove the tent villages that have appeared in Taksim and a park in the capital, Ankara. But the gatherings mark a challenge to a leader whose authority is built on three successive election victories.

"Let them attack, they can't stop us," shouted a member of the Turkish Communist Party, shouting through loudspeakers to a cheering crowd from on top of a white van in Taksim Square.

"The AK Party will go. This will be the end."

The protesters have built barricades of paving stones and corrugated iron on access roads to Taksim to try to protect themselves against a potential police assault. But their actions have brought gridlock to part of central Istanbul and it is unclear how long the authorities will tolerate their presence.

The square is lined by luxury hotels that should be doing a roaring trade as the summer season starts in one of the world's most-visited cities. But a forced eviction could trigger a repeat of the clashes seen earlier in the week.

Anger boils over

Erdogan takes the protests as a personal affront.

He has enacted many democratic reforms, taming a military that toppled four governments in four decades, starting entry talks with the European Union, reining in rights abuses by police and forging peace talks with Kurdish rebels to end a three-decade-old war that has cost 40,000 lives. Per-capita income has tripled in nominal terms and business has boomed under his rule.

But in recent years, critics say his style, always forceful and emotional, has become authoritarian.

Media have come under pressure, and the arrests of military and other figures over alleged coup plots as well as moves such as restrictions on alcohol sales have unsettled especially secular middle-class Turks who are sensitive to any encroachment of religion on their daily lives.

The fierce crackdown, condemned by foreign powers, on what started as peaceful protests in Gezi Park were the final straw, has caused simmering frustrations with Erdogan's leadership to boil over.

"These protests are partly a result of his success in economic and social transformation. There's a new generation who doesn't want to be bullied by the prime minister and who is afraid their lifestyle is in danger," said Joost Lagendijk, a former European parliamentarian and Istanbul-based academic.

Sources close to the AK Party that Erdogan founded in 2001, and which only a year later crushed traditional secular parties in elections, suggest a sense of siege within the leadership, with influential if disparate forces keen to remove Erdogan.

Citing a party source, the Radikal newspaper said an AK Party executive meeting on Saturday may discuss the possibility of calling early elections, although it could also change party rules to enable Erdogan to seek a fourth term as prime minister rather than running for the presidency.

Erdogan has made clear he has no intention of stepping aside – pointing to the AK Party's 50 percent of the vote in the last election – and he has no clear rivals inside the party or outside, with the opposition fragmented on the streets and in parliament.