By Nick Tattersall and Parisa Hafezi
ISTANBUL/ANKARA, June 6 (Reuters) - Turkish police clashed with demonstrators overnight ahead of the return of Prime Minister Tayyip Erdogan to a nation rattled by a week of protest against his leadership.
Erdogan returns from a visit to North Africa to face demands he apologise over a fierce police crackdown and sack those who ordered it, following six days of protests that have left two dead and more than 4,000 injured in a dozen cities.
Riot police fired tear gas at hundreds of demonstrators who threw stones at them and chanted anti-Erdogan slogans in the heart of the capital Ankara on Wednesday night, witnesses said.
In the eastern province of Tunceli, several hundred protesters set up a street barricade and threw stones at police who responded by firing water cannon. Istanbul, which has seen some of the heaviest clashes, was quiet overnight.
What began as a campaign against the redevelopment of a leafy Istanbul park has surged into an unprecedented show of defiance against the perceived authoritarianism of Erdogan and his Islamist-rooted AK Party.
Police backed by armoured vehicles have fired tear gas and water cannon on stone-throwing protesters night after night, while thousands have massed peacefully in recent days on Taksim Square, where the demonstrations first began.
The straight-talking prime minister left on Monday in a defiant mood, dismissing the protesters as looters and vowing the unrest would be over in a matter of days, comments that his critics said further inflamed tensions.
AK Party Deputy Chairman Huseyin Celik called on party members not to go to the airport to greet Erdogan on his return to avoid stirring trouble. Erdogan was expected to hold a news conference with his Tunisian counterpart before returning.
"Nobody should take it upon themselves to go and greet the prime minister in this situation. The prime minister does not need a show of strength," Celik said in a television interview.
In Taksim Square, protesters remained defiant.
"We have the momentum, with people like me going to work every day and coming back to attend the protests," said Cetin, a 29-year-old civil engineer who declined to give his surname because he works for a company close to the government.
"We should keep coming here to protest until we really feel we've achieved something," he said, one of thousands gathered on Taksim Square until late into the night.
"EVERYWHERE IS TAKSIM"
Deputy Prime Minister Bulent Arinc, formally in charge while Erdogan is away, has struck a more conciliatory tone, apologising for the initial police crackdown on peaceful campaigners in Taksim's Gezi Park and meeting a delegation of protesters in his office in Ankara.
"The powers that be continue to counter with violence, pressure and prohibitionist policies ... demands which are being expressed in a peaceful and democratic manner," a spokesman for the delegation said after meeting Arinc.
"We demand the removal from duty of those who gave the order to inflict force ... starting with the governors and police chiefs of Istanbul, Ankara and Hatay," he told reporters, referring to the areas worst affected by violence.
A second trade union federation representing hundreds of thousands of workers joined the protests on Wednesday, its members banging drums, trailing banners and chanting "Tayyip resign" as they marched on Taksim.
Around Ankara's Kugulu Park, a middle class area dotted with restaurants and bars, people chanted "dictator resign" and "everywhere is Taksim, everywhere is resistance" into the night as residents on balconies banged pots and pans in support.
Despite the protest, Erdogan remains by far the country's most popular politician, his blustering, 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 no obvious rivals inside or outside his party.
But he, and those around him, face a challenge calming the protests without appearing to lose face.
On Wednesday, a small group of people who read a statement in support of the protests were set upon in the Black Sea city of Rize, Erdogan's homeland and a stronghold of the AK Party, an attack that only ended after police intervened.
"Erdogan cannot backtrack now. It would mean defeat," said 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." (Additional reporting by Ece Toksabay and Ayla Jean Yackley in Istanbul, Jonathon Burch in Ankara; Writing by Nick Tattersall; Editing by Will Waterman and Giles Elgood)