The Turkish prime minister has blamed "extremist elements" for the riots that have swept his country in recent days.

Recep Tayyip Erdogan on Monday accused the main opposition Republican People’s Party (CHP) of playing an active role and working together with extremists.

He also said intelligence services were investigating foreign links to the anti-government demonstrations centred on Istanbul’s Taksim Square.

"People who are talking about a "Turkish Spring" in their coverage of events do not know Turkey," he said.

His comments came as he prepared to fly to Morocco for the start of a tour of North Africa, with commentators expressing surprise at his decision not to cancel the trip.

Meanwhile, police clashed with protesters in the capital, Ankara, as anti-government demonstrations stretched into a fourth straight day.

Al Jazeera's Idil Gungor reported that police fired tear gas and used pressurised water against demonstrators who chanted slogans. Most of the people in the crowd were secondary-school students, she said.

Police also fired tear gas at a group of protesters in an area close to Erdogan's offices in Besiktas neighbourhood of Istanbul. The protesters responded by hurling back stones.

On Sunday night, protesters in Besiktas used a mechanical digger to break police lines.

Taksim peaceful

Thousands of other protesters gathered on Monday in Taksim Square, the symbolic heart of the protests that erupted into violent clashes on Friday and have spread to cities across the country.

"Tayyip, resign!" they yelled, waving red flags and banners and blowing whistles.

The square remained peaceful until darkness fell. Later at night, tear gas was fired but it was not immediately clear where it came from.

Muammer Guler, the interior minister, told the Hurriyet newspaper that there had been more than 200 demonstrations in 67 cities. Hundreds of injuries have been reported.

Erdogan on Sunday renewed his calls for an end to the disturbances, saying: "If you love this country, if you love Istanbul, do not fall for these games."

The opposition CHP has denied involvement in the violence.

"Today the people on the street across Turkey are not exclusively from the CHP, but from all ideologies and from all parties," Mehmet Akif Hamzacebi, a senior party member, said.

The unrest erupted on Friday when trees were torn down at a park in Taksim Square under government plans to redevelop the area, but widened into a broad show of defiance against the governing, Islamist-rooted AK Party.

Conservative meddling

Erdogan has overseen a transformation in Turkey during his decade in power, turning its once crisis-prone economy into the fastest-growing in Europe.

He remains by far Turkey's most popular politician, but critics point to what they see as his authoritarianism and religiously conservative meddling in private lives in the secular republic.

Tighter restrictions on alcohol sales and warnings against public displays of affection in recent weeks have also provoked protests.

Erdogan, appearing on Sunday on television for the fourth time in less than 36 hours, justified the restrictions on alcohol as for the good of people's health.

"I want them to know that I want these [restrictions] for the sake of their health ... Whoever drinks alcohol is an alcoholic," he said.