A rise in tsunami sirens being stolen from several Auckland areas on the west coast is putting lives at risk, says Auckland Council.

Auckland Emergency Management (AEM) head of capability and public awareness Adam Maggs said the number of sirens either being stolen or vandalised has escalated in the past few weeks. He said it was unacceptable.

"These sirens are specifically designed for alerting and are of no use for any other purpose, including playing music, making this a malicious and wasteful act of vandalism."

Thieves and vandals have targetted sirens at Huia, Whatipu, Karekare, Piha and Te Henga.

"The loss of sirens means that the audible warnings for a tsunami threat at these locations may not be functioning at full capacity or as you might expect – for example, some areas may have fewer operating sirens," said Maggs.

The money to fix or replace the sirens comes out of the ratepayers' pockets, Maggs said.

"They are also not an 'off-the-shelf' product, which means they cannot simply be replaced."

AEM is currently looking into replacement options but sourcing products offshore, international shipping requirements and the long-term sustainability of a product prone to vandalism is weighing heavily.

Maggs says fortunately sirens are only one way to be informed of the threat of tsunami.

"Warnings will be sent by Emergency Mobile Alert [messages to your mobile phone], broadcast on radio and television or via the news media, and social media platforms," he said.

"And of course, if you are at the coast and feel an earthquake which is long or strong, move inland or to higher ground immediately."