Europe’s human rights watchdog has issued a strong warning on the dangers of new mass surveillance counter-terrorism measures being adopted by governments in the aftermath of the Paris and Copenhagen terror attacks.

Nils Muižnieks, the Council of Europe’s human rights commissioner, says proposals such as banning encryption, as advocated by David Cameron, and giving the security services unfettered access to digital communications suggests “little has been learned from the Snowden affair about the danger to human rights”.

The human rights watchdog also warns that plans to make internet companies responsible for removing content that “incites terrorism” without any possibility of being challenged in court are “highly problematic”.

In a report to the Council of Europe’s 47-member committee of ministers, Muižnieks, a Latvian political scientist, says governments need to be cautious in adopting new anti-terrorist legislation and urges them to reinforce democratic oversight of the security services which he describes as “woefully inadequate” across much of Europe.

“The aftermath of the Paris attacks has … seen a broader debate about counter-terrorism in France and Europe. Some proposals – giving security services unfettered access to digital communications, banning encryption, etc – suggest that little has been learned from the Snowden affair about the dangers to human rights, especially the right to privacy, of mass surveillance,” the human rights commissioner says in his report.

European interior ministers have given a high priority to trying to secure a EU-wide agreement to set up a passenger name record database tracking the movements of all passengers flying in and out of Europe and to securing the agreement of internet companies to take down material that promotes terrorism or extremism.

Floral tributes are laid outside the Great Synagogue in Copenhagen, scene of a gun attack. Photograph: Michael Probst/AP

It also comes as the home secretary, Theresa May, is due to join Barack Obama at a Washington summit on tackling international violent extremism. The US president is due to speak at the summit on Wednesday. It is expected to produce an action plan leading to a second meeting before the opening of the UN general assembly in September.

The White House has described the summit as highlighting “domestic and international efforts to prevent violent extremists and their supporters from radicalising, recruiting, or inspiring individuals or groups in the United States and abroad to commit acts of violence”.

It is expected, in particular, to include discussion of greater information-sharing on action to stem the flow of foreign fighters to and from Syria and Iraq. The home secretary is due to address the summit on Thursday in a closed session.

A Home Office spokesman said the summit would provide an opportunity to discuss issues such as the use of social media by terrorists and extremists to radicalise the vulnerable as well as programmes such as the Prevent strategy to counter them.