Internet users in Turkey were on Friday experiencing severe difficulties accessing social media after the country was plunged into new turbulence by the detention of its main pro-Kurdish leaders, correspondents and a watchdog said.

The messaging service WhatsApp was not working while users were also reporting severe problems accessing Twitter, Facebook, YouTube and other sites, AFP correspondents and Internet users said.

Prime Minister Binali Yildirm did not directly confirm that blocks were in place but acknowledged that "from time to time for security reasons we can use such measures".

"These are temporary measures. Once the danger is passed, everything returns to normal," he told reporters in Istanbul in televised comments.

The problems came after 11 MPs from the pro-Kurdish Peoples' Democratic Party (HDP), including its co-leaders Figen Yuksekdag and Selahattin Demirtas, were detained in an unprecedented crackdown.

The monitoring site Turkey Blocks said that Twitter, Facebook and YouTube were down in Turkey while restrictions had also been imposed on WhatsApp, Skype and Instagram.

The site, which monitors internet restrictions in Turkey, said this had been carried out by a "throttling" at Internet Service Provider (ISP) level including national providers like TTNet and Turkcell.

"Internet restrictions are increasingly being used in Turkey to suppress media coverage of political incidents, a form of censorship deployed at short notice to prevent civil unrest," it said.

It said that while there had been restrictions on Twitter and Facebook in the past, this was the first time that popular messaging services like WhatsApp were affected.

Users in the southeast of Turkey had last week reported major difficulties in using the internet.

Many internet-savvy Turks during such times turn to Virtual Private Networks (VPNs) to subvert the restrictions on public servers.