Warning sirens across the Islands continued to malfunction during yesterday's regular monthly test — just as they had during Saturday's tsunami scare — but state officials are working on adding new ones and repairing old ones.

Out of the state's 364 warning sirens, at least 24 failed to work yesterday.

On O'ahu alone, 15 of the island's 176 sirens were silent yesterday. On average, eight to 10 sirens are reported to malfunction during each month's tests, said Peter Hirai, deputy director of the city's Department of Emergency Management.

City officials theorized that more people were paying attention to yesterday's test and were more likely to report problems, Hirai said.

At the same time, city officials were still trying to determine exactly how many sirens malfunctioned during Saturday's tsunami warning.

Hirai emphasized that the statewide warning sirens are just one tool in Hawai'i's emergency communications system.

But he acknowledged that the number of sirens that malfunctioned yesterday "was higher than average. We're still trying to figure out why."

Kaua'i officials reported that six of their 43 outdoor signals did not work yesterday, along with one of their five indoor sirens.

On the Big Island, three of the island's 72 sirens definitely malfunctioned yesterday, and officials were reviewing seven more that might have failed.

"Every month, a few don't work for any number of reasons," Hawai'i County spokesman Hunter Bishop said. "It could be vandalism, age or weather-related."

Maui officials did not return calls.

Over the next four to five years, state Civil Defense officials are working on a plan to replace 118 mechanical sirens across the Islands with more reliable solar-powered battery ones and add 141 new solar-powered sirens, which would increase the state's inventory of sirens to 505.

The cost of sirens varies, but they average around $85,000 each, said state Civil Defense spokeswoman Shelly Ichishita.

The $10.5 million for the project was released last year as part of the federal stimulus plan, Ichishita said, but Civil Defense officials hope the Legislature adds another $8.3 million for even more upgrades.

Honolulu Councilman Donovan Dela Cruz says the project is taking too long.

He introduced a resolution in 2007 urging city and state officials to upgrade O'ahu's warning sirens, and will introduce another on Thursday.

"We need to get moving," said Dela Cruz, whose district include's O'ahu's North Shore. "I'm glad we were able to avoid a catastrophe, but this is just another concrete example that we need sirens in places where people can hear them. It's long overdue."