Suddenly, in the middle of the New York night, Edward Snowden's face appeared deep in a public park.

A 1.2-meter-high, 45-kg sculpted bust of the whistleblower, now exiled in Russia, was sneaked into the Brooklyn borough's Fort Greene Park on Monday before dawn.

Animal New York, the website for city news that first reported the incident, said the mysterious perpetrators were a small group of artists - admirers of the former US government contractor who had leaked classified information from the US National Security Agency to the media.