ISTANBUL/ANKARA (REUTERS) - Thousands of supporters welcomed back Turkish Prime Minister Tayyip Erdogan from a North African tour on Friday in a show of strength after a week of violent anti-government demonstrations across the country.

Mr Erdogan addressed crowds from an open-top bus at Istanbul airport in a speech also broadcast live on television, as supporters, who had blocked roads to the airport for hours, chanted his name.

"We stood strong, but we were never stubborn... We are together, we are unified, we are brothers," Mr Erdogan told tens of thousands of his ruling party faithful.

Anti-government protesters also gathered in their thousands in central Istanbul and Ankara awaiting a speech that could appease or aggravate the crowds after a week of violent unrest.

Some of the demonstrators in Istanbul's Taksim Square chanted "Tayyip resign", while others sang and danced. In Ankara's Kugulu Park, thousands chanted anti-government slogans, sang the national anthem and swigged on beer.

What began as a campaign against planned construction on a leafy park in a corner of Taksim Square has grown into an unprecedented display of public anger over the perceived authoritarianism of Mr Erdogan and his Islamist-rooted AK Party.

Police backed by armoured vehicles and helicopters have clashed with groups of protesters night after night, leaving three dead and some 4,000 injured, while thousands of Mr Erdogan's opponents have massed peacefully in Taksim, surrounded by barricades of torn-up paving stones and street signs.

"It's all up to Erdogan and what he says right now. He will decide the fate of this resistance, whether it will calm (down) or escalate," said Mr Mehmet Polat, 42, a ship captain who has not worked all week, coming instead to protest at Taksim.

"These people have been here for days. He has to understand it is for a reason," he said.

Mr Erdogan has so far struck a defiant tone. Speaking in Tunis on Thursday, he condemned the "burn and destroy" tactics of some of those involved in the protests, and promised to press ahead with the plans for Taksim that triggered the unrest.

"If you say: 'I will hold a meeting and burn and destroy', we will not allow that," he told reporters after meeting his Tunisian counterpart. "We are against the majority dominating the minority and we cannot tolerate the opposite."

He said that "terror groups", including one that claimed responsibility for a Feb 1 bombing at the United States Embassy in Ankara, were manipulating the crowds. Seven foreigners were among those arrested, he said.

The protesters are of a variety of political stripes, including far leftists, nationalists, environmentalists and secular Turks, and their numbers at Taksim have swollen at points to more than an estimated 100,000.

But despite the unrest, Mr Erdogan remains by far Turkey's most popular politician, his assertive style and common touch resonating with the conservative Islamic heartland.

His AK Party has won an increasing share of the vote in three successive elections and holds around two thirds of the seats in parliament. A man who rarely bows to any opposition, he clearly has no intention of stepping down and there are no obvious rivals inside or outside his party.

Still, he faces a challenge in calming the protests without appearing to lose face.

"Erdogan cannot backtrack now. It would mean defeat," said Mr Ali Aydin, 38, a car dealer in the Tophane neighbourhood of Istanbul, a conservative bastion in the mostly Bohemian district around Taksim Square. "Weakness would destroy the party."