Historic military equipment, reported to be two World War II bombs, have been found by fishermen near Lyttelton.

A Police spokeswoman said the New Zealand Defence Force bomb disposal team is working with police to ensure the items are safe and there is no risk to the public.

A Christchurch firefighter took to Twitter and said, "Well I never! Station 28 just got turned out to a 111 call for an explosion," he said.

"It was the first detonation of two World War II bombs dredged up out of Lyttelton Harbour. We got there just in time for the second one."

The Herald has contacted the NZ Defence Force for comment.