Turkey's prime minister hit back at suggestions that new Internet regulations will limit freedom of expression, ahead of a planned demonstration in Istanbul against the curbs on Saturday.

"These regulations do not impose any censorship at all on the Internet ... On the contrary, they make it safer and freer," Recep Tayyip Erdogan said in Istanbul.

He also denied that the regulations, passed by parliament late on Wednesday, meant that government authorities would have access to Internet users' personal information.

"Never. It is out of the question that people's private data will be recorded," said Erdogan, prime minister since 2003.

The new curbs provoked a storm of protest at home and abroad, with critics saying they were an attempt by Erdogan to stifle dissent and stop evidence of high-level corruption being seen online.

They give the telecoms authority the power to order a webpage blocked without the need for a court order if the content is deemed to infringe someone's privacy or as being offensive.

The timing in particular raised eyebrows because it comes as Erdogan deals with a major and deeply embarrassing corruption probe implicating members of his inner circle.

Human Rights Watch said the restrictions raise concerns that a "defensive government is seeking to increase its power to silence critics and to arbitrarily limit politically damaging material online."

European Parliament chief Martin Schulz called them a "step back in an already suffocating environment for media freedom", while Washington also expressed misgivings.

Erdogan has portrayed the investigation as a plot against him by people within the Turkish police and judiciary loyal to Fethullah Gulen, an Islamic preacher living in the United States.

His government has sacked or moved to different jobs thousands of police and prosecutors ahead of important local elections on March 30 which could determine whether he runs for president in August.