Emergency crews responding to the deadly tornado in Alabama on 1 March were frustrated by a jammed mobile phone link in the immediate area, but were slow to switch to an interoperable $18m emergency communications system instead, officials have said.

"People were frustrated, but all they had to do was turn on their radios," said Alabama's homeland security director, Jim Walker, in comments to a reporter that were confirmed by his spokeswoman yesterday.

The reason emergency crews used the mobile network from Southern LINC Wireless was that they were accustomed to using it for day-to-day communications and had fallen into a habit of doing so, officials said.

Southern LINC Wireless confirmed that a mobile phone tower in the Coffee County area near the tornado experienced increased volume, but a spokeswoman said the network was not overwhelmed, contrary to a comment by one company official. She said additional capacity was added immediately after the storm. Increased volumes on mobile phone links often result in inability to complete all calls.

In all, nine people were killed in the storm, which levelled a town's high school and other buildings.

In 2004, Alabama's Department of Homeland Security used $18m in a federal grant to buy equipment to provide interoperability between different radio systems used by various emergency response agencies, officials said.

Slowness in communication after the storm was linked to a higher level of frustration, but not to any loss of life, officials said.