A protester waves a Turkish flag in front of riot police during a demonstration at Taksim square in central Istanbul June 25, 2013. Turkish anti-terrorism police detained 20 people in raids in the capital Ankara on Tuesday in connection with weeks of anti-government protests across the country, media reports said. [Photo/Agencies]

ANKARA, Turkey - Turkish police on Tuesday detained at least 20 people allegedly involved in violent protests, as the country's prime minister continued to lash out at protesters - and a BBC journalist - he claimed were part of a conspiracy to harm Turkey.

Meanwhile, hundreds of protesters marched to Istanbul's central Taksim square, this time to denounce a court decision that - pending trial - freed police officer accused of killing a demonstrator during the anti-government protests that have swept the country since May 31. Police surrounded the square, blocking their access.

At least three demonstrators and a police officer were killed in the protests that began in Istanbul following a heavy-handed police clampdown on peaceful activists. They quickly turned into widespread expression of discontent with what critics have said is Prime Minister Recep Tayyip Erdogan's increasingly authoritarian way of governing.

Erdogan, who came to power a decade ago denies the accusation, and frequently points at elections in 2011 that returned his party to power for a third successive term with 50 percent of the vote.  

One of the protesters was killed by a bullet fired by police during a demonstration in Ankara on June 1. A court on Monday released the officer from custody pending trial, on the grounds that the shooting may have been accidental. But some see the release as proof that Turkish authorities are too lenient toward police.

The state-run Anadolu Agency said police searched some 30 addresses in the capital, Ankara, and rounded up 20 people with alleged links to "terror" groups and suspected of "attacking police and the environment" during the protests.

Erdogan holds unspecified foreign forces, bankers and media outlets responsible for the protests that had largely subsided until the court freed the police officer.

In an address to members of his Islamic-rooted party in Parliament, Erdogan reiterated that the protests were orchestrated by forces wanting to prevent Turkey's rise.

He repeated his claim that the same conspiracy was at work in Brazil, saying both countries had paid off debts to the International Monetary Fund.

Mass rallies in Brazil were set off this month by a 10-cent hike in bus and subway fares in Sao Paulo, Rio de Janeiro and elsewhere. The protests soon moved beyond that issue to tap into widespread frustration in the South American nation over a range of issues, including high taxes and woeful public services.

"From the start, some people, internally and externally, have tried to portray the protests as totally innocent and just, and the police of having systematically used force," Erdogan said. "Certain media in Turkey were lead provocateurs. The foreign media took part in these operations."

He targeted a Turkish BBC reporter who tweeted about a forum held by protesters, where participants reportedly suggested a six-month boycott of goods that they said would help slow down the economy. Without mentioning her by name, Erdogan accused Selin Girit of being "part of a conspiracy against her own country".

"Their aim is to prevent democracy, to harm Turkey's economy, to hit tourism," Erdogan said.

Two days earlier, Ankara's mayor had accused Girit of being a British government agent and started a campaign on Twitter to apparently try to discredit her, prompting the BBC to issue a statement on Monday that said "it is unacceptable for our journalists to be directly targeted this way".

The BBC's global news director Peter Horrocks said "a large number of threatening messages" were sent to the reporter and he was concerned by the Turkish authorities' campaign to "discredit the BBC and intimidate its journalists".

On Monday, US President Barack Obama spoke with Erdogan for the first time since the protests began. According to the White House, the two leaders discussed "the importance of nonviolence and of the rights to free expression" as well as the right of assembly and a free press.

Thorbjorn Jagland, the secretary-general of the 47-member Council of Europe, the continent's human rights watchdog which is based in Strasbourg, France, met with Erdogan in Ankara on Tuesday.

Jagland said that he had brought up a number of human rights issues concerning the protests, including the firing of tear gas by police inside an Istanbul hotel where some protesters had taken refuge.

"The Court of Human Rights in Strasbourg has a number of judgments related with this," Jagland said. "For instance, the court has said that the use of tear gas inside a room is not acceptable and this happened at one hotel at least."

"It is important to convey that the authorities have responsibility to react in a way that doesn't trigger further and more violence," he said.

In his speech Tuesday, Erdogan accused the hotel, Divan, and the Koc family that owns it - Turkey's richest family - of aiding criminals.

"Those who clashed with police went there. Its owners provided them with hospitality," Erdogan said. "You know it is against the law to harbor criminals."