Turkey's opposition party leader accused the prime minister on Monday of escalating tensions and dragging the country "into the fire" as anti-government protests that have led to three deaths hit their 11th straight day.

Prime Minister Recep Tayyip Erdogan headed a Cabinet meeting to discuss the protests, the first serious challenge to his 10-year rule. On Sunday he made a series of fiery speeches in three cities, saying the government's patience was running thin, demanding an end to the protests and threatening to hold those who don't respect his government to account.

Erdogan has also called for major pro-government rallies in Ankara and Istanbul next weekend, apparently aiming to intimidate the protesters by showing that he, too, can get large numbers out on the street.

The Hurriyet newspaper on Monday quoted Kemal Kilicdaroglu, the head of the opposition Republican People's Party, urging Erdogan to reduce tensions.

"Why is the prime minister being so stubborn toward his people? He should not do it," Kilicdaroglu said. "We are witnessing a prime minister who is trying to hold on to power by creating tensions."

"A policy that feeds on tension will drag society into the fire," he added.

Crowds of protesters swelled into the tens of thousands in Istanbul's Taksim Square and city centers in Ankara and Izmir as Erdogan delivered his speeches. Police broke up the protest near government buildings in Ankara with tear gas and water cannons.

The Turkish Human Rights Foundation said at least 12 people were detained in Ankara. It added that 13 were detained in the city of Adana for allegedly "inciting people into rioting" through social media. They were questioned by a court, which then released them, the state-run Anadolu Agency reported. A further 25 protesters were detained in Izmir for Twitter posts last week. They were also later released.

The protests were sparked by a violent police crackdown May 31 on a sit-in at a park in Taksim Square to prevent a redevelopment project that would replace the green space with a replica Ottoman Barracks. They have since spread to 78 cities across the country.

Protesters are venting their anger at what they say are Erdogan's growing autocratic ways and his attempts to impose a religious and conservative lifestyle. Erdogan, a devout Muslim, says he is committed to Turkey's secular laws and denies charges of autocracy.

On Sunday he denied that he was raising tensions and insisted the protests are a ploy to undermine his government, which was elected with 50 percent support in 2011.

Protesters on Monday continued to occupy the park in Taksim Square.

"I am here because I don't want (Erdogan) and his government anymore, said 26-year-old Melisa Colakoglu. "Because it is not democratic."

Police in Ankara again removed tents from a small park where protesters have gathered to show of support for the Istanbul protesters.

On Monday, the country's Doctors Association said it had asked authorities to reveal the chemical content of the tear gas it was firing.

"We note that those chemical agents have been used intensively in the past two weeks," Bayazit Ilhan, the association's secretary-general, told reporters. "The protesters and doctors have serious concerns about the content of chemicals used and the amount (used)."

The association said tear gas could lead to serious health problems, including asthma attacks, breathing problems and high blood pressure, and recommended that its use be banned.

It said close to 5,000 people had sought medical care since the protests began due to tear gas or injuries caused by plastic bullets, beatings or being hit by tear gas canisters. Ten people had lost an eye and 18 had received blows to the head, it added.

Human rights groups have accused police of using excessive force on protesters. Even Turkey's allies like the United States and the European Union have expressed concerns over the number of people who have been hurt.

Two protesters have died, as well as a police officer who fell into an underpass while chasing protesters. The government says some 600 police officers were also hurt.