Turkey's powerful populist leader Recep Tayip Erdogan shows no signs of flinching against masses of angry protestors who brand him a dictator, dismissing them as "a handful of vandals".

Thousands have rallied, complaining that he is pushing conservative, Islamist-flavoured policies in Turkey - a country with a predominantly Muslim population but a staunchly secular state.

"I'm not a dictator. It's not even in my blood," he responded on Sunday.

Analysts say it is too early to claim the demonstrations would weaken his reputation as the most influential leader since Mustafa Kemal Ataturk - the father of modern Turkey. Erdogan is expected to run for president in elections next year.

"He is a prime minister elected by 50 percent of the population only two years ago. He's pretty confident," Hugh Pope of the International Crisis Group told AFP.

But he added: "It would be really good if he were engaged with the mainstream involved in the protests."

Demonstrators of diverse backgrounds have flooded squares in major cities across the country over the past four days, yelling: "Dictator, resign!"

The outburst has thrown up one of the toughest challenges to Erdogan's government since it came to power in 2002.

His response has not soothed the crowds enraged by what they see as curbs to their freedom by his Justice and Development Party (AKP).

A local environment campaign to save a park at Istanbul's main Taksim square, the symbolic heart of demonstrations, swelled from Friday into a general protest against Erdogan's government.

But it was not the first challenge the Turkish leader has faced.

In 2007, hundreds of thousands poured into the streets in big cities and rallied in protest against his pick for president - Abdullah Gul, whose wife wears an Islamic headscarf. The prime minister weathered that outcry.

In power since 2002, Erdogan has brought relative stability to Turkey after years of rocky coalition governments, building the country into a regional political and economic power.

But his authoritarian style and zero-tolerance of criticism has proved a major test for democracy in the nation at the crossroads of east and west.

Erdogan's regular attacks on the media and a tendency to use the courts to silence his enemies - including a campaign taking on the powerful military establishment - have added to fears about rights in a country which has long sought to join the European Union.

Under Erdogan's rule, Turkey has been blacklisted as the leading jailer of journalists worldwide by rights groups.

Hundreds of military officers, academics and lawyers are also in detention - most of them accused of plotting against the government, in what critics say is a policy to stifle dissent.

A practising Muslim, Erdogan has pioneered contentious legislation that will curb the sale and advertising of alcohol if his ally Gul signs it into law.

That has outraged his secular opponents who charge that he wants to Islamise the officially secular country.

The 59-year-old politician - who once sold lemons on the streets of Istanbul to fund his schooling - has enjoyed overwhelming electoral support, casting himself his image as a man of the people with his tough-talking style and swagger.

Observers say he is now setting his sights on the presidency, hoping to change the constitution to give the president US-style executive powers before running for the post himself next year.

"We're talking about a government which has been in power since 2002 and which has continuously increased its votes. This is naturally leading to a burnout, as well as excessive self-confidence," said Kamer Kasim of the Ankara-based think tank USAK.

He said that Erdogan's tough-talking style was not unique to majority leaders but shared by opposition party politicians in Turkey.  "Politics is tough in Turkey and politicians believe speaking tough turns into more votes."

Despite his humble origins, Erdogan climbed the political ladder, bouncing back from a stint in jail in 1999 - accompanied by a ban from holding office - for reciting an Islamic-motivated poem during a public speech while he was mayor of Istanbul. He won local elections in 1994 to become mayor of Istanbul, Turkey's largest city, holding the post until 1998. After his release from jail, he formed the AKP in 2001.

As prime minister, Erdogan returns often to his humble roots - he chats with taxi drivers, pays visits to poor families and stops his convoy in the mornings to buy bread from local vendors.

Analysts warned that he could not remain indifferent to public pressure.

"He is quite pragmatic," Pope said, and knows that any weakening of his position would threaten his efforts to settle a three-decade-old Kurdish insurgency in the southeast.

Erdogan may earn himself a lasting legacy if he succeeds in forging an elusive peace with the Kurdish rebels, Pope said - a move the prime minister launched despite considerable political risks.