The Guardian's articles about mass surveillance conducted by GCHQ and the US NSA have been honoured by the civil rights group Liberty. The newspaper was named Independent Voice of the Year at Liberty's annual awards ceremony in central London on Monday evening.

The Guardian revelations about interception of online communications, eavesdropping on international politicians and tapping of fibre-optic cables were based on documents leaked by former NSA contractor Edward Snowden. The award "recognises the courage it requires to speak out against injustice when others will not, to make a stand when no one else will and to put the truth before all else, even at great cost".

Shami Chakrabarti, director of Liberty, said: "Whatever your position on blanket surveillance, the people and their parliament have a right to debate it and there can be no debate about what we do not know. In a time of deceit, telling the truth seems revolutionary. Spy chiefs should reflect on whether their occasional inconvenience isn't essential to the democracy they serve."

The Guardian's editor, Alan Rusbridger, accepted the award. He said: "What was worrying Edward Snowden was that we were, unknowingly, sleep-walking into a society where the infrastructure of total surveillance was being built behind our backs, without any discussion or wide public knowledge. This does need to be discussed, as calmer heads in security agencies now recognise. I am very proud to pick up this award in recognition of the Guardian's role in stimulating that necessary debate."

Other awards included human rights campaigner of the year: Caroline Criado-Perez for restoring a woman to Britain's banknotes. Liberty's human rights lawyer of the year award went to Stephanie Harrison QC for her work supporting migrants and refugees in legal cases. Doreen Lawrence, now Lady Lawrence, received Liberty's lifetime achievement award for her pursuit of justice following the murder of her son, Stephen. Liberty's Far From Home award went to Susan Smith, Colin Redpath, Karla Ellis and Courtney Ellis for their campaigns to extend human rights protections to soldiers serving overseas following the deaths of members of their families in Snatch LandRovers in Iraq.