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.

The activists hoisted the bust to the top of a US Revolutionary War memorial, adding Snowden's name to a column, the website reported.

It said the group allowed it to document the installation of the statue on condition that it not reveal the identities of the artists.

Snowden's artistic appearance was short-lived.

At daybreak, parks officials ordered the sculpture removed. By evening, the bust was being held by police, pending an investigation.

The idea for the tribute was conceived by two New York City-based artists, joined by a West Coast sculptor, the website said.

They said they had "updated" the memorial to US prisoners of war who died during the US Revolutionary War "to highlight those who sacrifice their safety in the fight against modern-day tyrannies".