San Francisco, Sep 12 (IANS/EFE): Internet giant Yahoo has said it was threatened by the US government to make it cooperate with the administration and provide its users' data under the National Security Agency's (NSA) controversial vigilance programme, PRISM.

"We had to fight every step of the way to challenge the US government's surveillance efforts. At one point, the US government threatened the imposition of $250,000 in fines per day if we refused to comply," Ron Bell, Yahoo's general counsel, wrote in the company's blog post Thursday.

The case dates back to 2007 when the US government amended a law enabling it to seek users' data from online service providers.

Yahoo refused to comply as it considered the move "unconstitutional" and appealed to the US Foreign Intelligence Surveillance Court (FISC).

The web company, which received threats from the government during this time, eventually lost the case and was forced to share the data it was asked for.

However, according to Bell, it focused its efforts on getting the case archive declassified so that the public could see the truth for themselves, something it has finally achieved.

"We are working hard to make the materials from the FISC case public," said Bell, whose efforts ensured 1,500 pages from the case being declassified by the FISC.

NSA's controversial programme, PRISM, the existence of which was brought to public knowledge through leaks by former NSA analyst Edward Snowden in 2013, made it obligatory for technology firms to share information about their users with the government.

Besides Yahoo, several other reputed US firms provided information to the NSA under this programme, including Google, Facebook, Apple, AOL and Microsoft.

"We treat public safety with the utmost seriousness, but we are also committed to protecting users' data. We will continue to contest requests and laws that we consider unlawful, unclear, or overbroad," Bell said.