Peace activists have attacked and deflated a large inflatable globe housing a satellite dish at a top secret New Zealand spy base in protest at United States military actions.

The group, calling itself ANZAC Ploughshares, said it cut through fences and razor wire and avoided electronic sensors before using a sickle to slash one of two 30-metre white globes at the Waihopai base near Blenheim at the top of the South Island.

The base is described as a satellite communications monitoring facility, but peace campaigners say it is part of a global signals interception network called Echelon.

"The Echelon spy network, including Waihopai, is an important part of the US government's global spy network and we have come in the name of the Prince of Peace to close it down," said Ploughshares in a statement.

It said the attackers built a shrine and prayed "to remember the people killed by United States military activity".

Three men, one of whom was a Dominican priest, were arrested at the site.

New Zealand Prime Minister Helen Clark, who is also in charge of the security services, condemned the attack.

"It's a senseless act of vandalism, but it will now be dealt with by police," her spokeswoman said.

Ploughshares said Ms Clark and the New Zealand government were privately supporting the war in Iraq while publicly condemning it.

-Reuters