Dear Prime Minister,

We have joined together as an international coalition of free speech, media freedom and human rights organisations because we believe that the United Kingdom government's response to the revelations of mass surveillance of digital communications is eroding fundamental human rights in the country. The government's response has been to condemn, rather than celebrate, investigative journalism, which plays a crucial role in a healthy democratic society.

We are alarmed at the way in which the UK government has reacted, using national security legislation against those who have helped bring this public interest information to global attention. We are concerned about:

• The use of Schedule 7 of the Terrorism Act 2000 to detain the Brazilian media worker, David Miranda on 18 August 2013 at London Heathrow Airport. Miranda was carrying journalistic material on behalf of the UK's Guardian newspaper and is the partner of the journalist, Glenn Greenwald, who broke the story of mass surveillance of digital communications by the UK and USA

• The sustained pressure against the UK's Guardian newspaper for reporting the disclosures of whistleblower, Edward Snowden, including sending officials to force the Guardian to destroy hard drives allegedly containing information from Snowden

• Your call on 16 October 2013 for a House of Commons Select Committee to review whether the Guardian has damaged national security by publishing material provided by Edward Snowden, and a subsequent announcement that the review will be conducted by the Home Affairs Select Committee as part of their inquiry into anti-terrorism.

We believe these actions clearly violate the right to freedom of expression, which is protected under British, European and international law. Under such laws, the right to freedom of expression includes the protection of both journalists, and those that assist them in the course of their vital work.

The right to freedom of expression and media freedom enable the free flow of information in order for the public to hold their governments to account. While the protection of national security can be a legitimate ground for restricting the right under international law, such restrictions are narrowly defined. Governments must show that a restriction is necessary to achieve a legitimate purpose and must be proportionate to the aim pursued. The presumption in favour of freedom of expression requires governments to demonstrate that the expression will actually harm national security; it is not sufficient to simply say that it will.

National security should never be used to justify preventing disclosures of illegalities or wrongdoing, no matter how embarrassing such disclosures may be to the UK or other governments. In the case of Snowden and the Guardian, the disclosures have facilitated a much-needed public debate about mass surveillance in a democracy, and exposed the possible violation of the fundamental human rights of millions of people worldwide. As such, no liability should be incurred as the benefit to the public outweighs the demonstrable harm to national security.

We also believe that this use of national security will have dangerous consequences for the right to freedom of expression and media freedom in the UK and beyond, creating a hostile and intimidating environment and discouraging those who could reveal uncomfortable truths and hold those in power to account. We are concerned that this will further create negative consequences for the reputation of the UK as an advocate for the protection and realisation of the right to freedom of expression and media freedom worldwide. States with little regard for the human rights of their people will seek to use the UK's example to legitimise their own repressive practices.

The UK has a strong history of democracy, and while targeted surveillance may play an important role in protecting national security, in doing so it should not erode the very values it seeks to protect. We call on you to honour the UK's international obligations to defend and protect the right to freedom of expression and media freedom, and to end the UK government's pressure on the Guardian and those who assist them.

Yours Sincerely,

Gergana Jouleva, Access to Information Programme, Bulgaria

Mircea Toma, ActiveWatch, Romania

Ahmad Quraishi, Afghanistan Journalists Center

Remzi Lani, Albanian Media Institute

Thomas Hughes, ARTICLE 19, international

Zuliana Lainez, Asociacion Nacional de Periodistas del Peru (ANP)

Khaled Amami, Association of Citizenship and Digital Culture (ACCUN), Tunisia

Jasna Milanovic, Association of Independent Electronic Media, Serbia

Hans de Zwart, Bits for Freedom, Netherlands

Guilherme Alpendre, Brazilian Association for Investigative Journalism

Yuri Dzhibladze, Center for the Development of Democracy and Human Rights, Russia

Ramana Sorn, Cambodian Center for Human Rights

Laura Tribe, Canadian Journalists for Free Expression

Olexandra Matviichuk, Center for Civil Liberties, Ukraine

Ioana Avadani, Center for Independent Journalism, Romania

Masjaliza Hamzah, Centre for Independent Journalism, Malaysia

Paul Dawnson Formaran, Center for Media Freedom and Responsibility, Philippines

Dr Leila Alieva, Center for National and International Studies, Azerbaijan

Edison Lanza, Centro de Archivos y Acceso a la Información Pública (CAinfo), Uruguay

Cristian Horchert, Chaos Computer Club, Germany

Kate Watters, Crude Accountability, USA

Jillian York, Electronic Frontier Foundation, international

Jo Glanville, English PEN

Shiva Gaunle, Federation of Nepali Journalists

Karim Lahidji, FIDH / International Federation for Human Rights

Andres D'Alessandro, Foro de Periodismo Argentino, Argentina

Chiranuch Jiew, Foundation for Community Educational Media (Prachatai), Thailand

Trevor Timm, Freedom of the Press Foundation, USA

Ayushjav Tumurbaatar, Globe International Center, Mongolia

Eka Popkhadze, GYLA, Georgia

Artus Sakunts, Helsinki Citizens' Assembly, Armenia

Avetik Ishkhanyan, Helsinki Committee of Armenia

Danuta Przywara, Helsinki Foundation for Human Rights, Poland

Eldar Zeynalov, Human Rights Center of Azerbaijan

Rasul Jafarov, Human Rights Club, Azerbaijan

Robert Ssempala, Human Rights Network for Journalists-Uganda

Sanar Yurdatapan, Initiative for Freedom of Expression, Turkey

Emin Huseynov, Institute for Reporters' Freedom and Safety (IRFS), Azerbaijan

Mayumi Ortecho, Instituto Prensa y Sociedad, Latin America

Elizabeth Ballantine, Inter American Press Association

Ann-Sofie Nyman, International Partnership for Human Rights, Belgium

Alison Bethel McKenzie, International Press Institute

Yevgeniy Zhovtis, Kazakhstan International Bureau for Human Rights and Rule of Law

Mariya Yasenovska, Kharkiv Regional Foundation 'Public Alternative', Ukraine

Alban Muriqi, Kosova Rehabilitation Centre for Torture Victims

Shami Chakrabarti, Liberty, UK

Prof. Amal Jamal, Media Center for Arab Palestinians, Israel

Meri Bekeshova, Media Workers' Trade Union of Kyrgyz Republic

Nani Jansen, Media Legal Defence Initiative, UK

Soe Myint, Mizzima, Myanmar

Ludmilla Alexeeva, Moscow Helsinki Group

Omar Faruk Osman, National Union of Somali Journalists (NUSOJ)

Andre Loconte, Net Users' Rights Protection Association (NURPA), Belgium

Gunnar M. Ekelove-Slydal, Norwegian Helsinki Committee

Alberto Cerda, ONG Derechos Digitales, Chile

Makereta Komai, Pacific Islands News Association

Owais Aslam Ali, Pakistan Press Foundation

Mousa Rimawi, Palestinian Center for Development and Media Freedoms

Larry Siems, PEN American Center

Tasleem Thawar, PEN Canada

Laura McVeigh and Anders Heger, PEN International

Gus Hosein, Privacy International

Natalia Taubina, Public Verdict, Russia

Christophe Deloire, Reporters Without Borders, international

Oleksandra Sverdlova, No Borders Project, Social Action Center, Ukraine

Gayathry Venkiteswaran, Southeast Asian Press Alliance

Nalini Elumalai, Suara Rakyat Malaysia (SUARAM)

Alison Meston, WAN-IFRA, international

Maria Pia Matta Cerna, World Association of Community Radio Broadcasters (AMARC)

Arthur Gwagwa, Zimbabwe Human Rights NGO Forum