(CNSNews.com) - In an embarrassing security breach, anti-war activists in New Zealand early Wednesday broke into a communications facility they say is part of a global surveillance system that benefits the U.S. anti-terrorist campaign.

Three men were arrested after members of a group calling itself ANZAC Ploughshares said they cut through fences and slashed one of two giant white radomes covering satellite dishes, deflating the ball-shaped structure.

Center-left Prime Minister Helen Clark called the incident "a senseless act of criminal vandalism," but she declined to comment further on a security matter. "Our focus today is on the steps we're going to take to support the police with the criminal investigation and to start repairing the damage," she told reporters.

Three men later appeared in a district court in the small town of Blenheim and were remanded in custody. They were charged with criminal damage and entering with the intention of committing a crime, but they could face more serious sabotage charges.

The Waihopai base on New Zealand's South Island is operated by the Government Communications Security Bureau (GCSB). The Wellington-based agency says its functions are to collect and provide the New Zealand government with foreign intelligence, and to provide advice and expertise to ensure that the government's official information is protected.

Groups that have been protesting against the site for years claim it is part of a global eavesdropping network providing intelligence to the U.S. National Security Agency, and involving listening stations in Britain, Australia, New Zealand and Canada.

The alleged system, dubbed Echelon, was investigated by the European Parliament in 2001, following claims that it had been abused to benefit U.S. firms bidding for international contracts. The inquiry concluded that the system did exist, tracked mostly satellite-based messages, but also had the capacity to monitor telephone calls, faxes and emails.

The inquiry's report, debated by the parliament just days before 9/11, named the Waihopai base as one of the cogs.

In a statement, Ploughshares said its action was "responding to the Bush administration's admission that intelligence gathering is the most important tool in the so-called War on Terror."

"This war will have no end until citizens of the world refuse to let it continue," it said.

The group said its members, one of whom it described as a Dominican priest, had cut their way through three fences, including an electrified one, before attacking the dome. Then they "knelt in prayer to remember the people killed by United States military activity."

The GCSB is investigating what it described as a "deeply disturbing" breach of security. Agency director Bruce Ferguson said security cameras at the site had proven ineffective because of heavy fog.

Ferguson dismissed as an urban myth claims that the radomes, known colloquially as "golf balls," are designed to hide the direction in which the antennae are pointing. They serve to protect the antennae from exposure to the elements.

A group not involved in the incident, but which has protested against the Waihopai base for decades, congratulated Ploughshares on the action.

"Despite being under nominal New Zealand control, it is, in everything but name, an American spy base operating on New Zealand soil and at our expense," said Anti-Bases Campaign spokesman Murray Horton.

The anti-war campaigners believe that the base has provided information that has helped U.S. military operations in Iraq and Afghanistan.

Clark's Labor government opposed the war against Iraq, but sent Special Air Service (SAS) troops to Afghanistan to help in the U.S.-led campaign against the Taliban and al-Qaeda after 9/11, and since then has had an Army provincial reconstruction team deployed in Bamyan province.

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