London, Aug 30 (IANS): Whistle-blowing website WikiLeaks has "accidentally" released thousands of US diplomatic cables containing names of top secret sources, whose lives may now be in danger, a media report said Tuesday.

Around 134,000 documents were published by the website. They have names of journalists, human rights activists and academics who spoke to US diplomats posted in other countries. Their identities were marked with a warning "strictly protect", the Daily Mail said.

When former WikiLeaks spokesman Daniel Domscheit-Berg left the group last year, he took with him some material, including the documents, with him. He later returned the material.

The details were never supposed to be revealed.

However, founder Julian Assange -- in an apparent mix-up -- released all the documents online.

WikiLeaks had obtained over 250,000 US State Department documents since last year.

Among those named in the current files are a UN official in West Africa and a foreign human rights activist working in Cambodia. They also contain names of informants to the US missions in Israel, Jordan, Iran and Afghanistan.

German newspaper Der Freitag said the documents were online in a password-protected file named "cables.csv". The file was easy to find along with the password to unlock it.

Assange had stored the encrypted file on a sub-directory of the group's server. It was not searchable on the internet by anyone who did not have previous knowledge of its location.

Assange later reportedly gave the password to an "external contact".

WikiLeaks wrote on Twitter about the leak: "There has been no 'leak at WikiLeaks'. The issue relates to a mainstream media partner and a malicious individual."