Martin Winter, 50, and Nathan Winter, 23, of Marlie Farm, Shortgate, near Ringmer, spoke only to confirm their names and enter their pleas at Lewes Crown Court.

Geoffrey Wicker, 49, and Brian Wembridge, 63, died tackling a blaze at the firework depot in Sussex on December 3, 2006.

Twelve other people were injured in the explosions and blaze, at Festival Fireworks, near Ringmer, including nine firefighters and a police officer.

The company, now known as Alpha Fireworks Ltd, has been summonsed for breaches of the manufacture and storage of Explosive Regulations 2005.

A not guilty plea was also entered for the firework company which faces two charges of contravening health and safety legislation.

Mr Wicker, a retained firefighter, and Mr Wembridge, a fire service cameraman, were both long-serving members of East Sussex Fire and Rescue Service.

They received full brigade honours at their funeral services.

Judge Richard Brown released the Winters on unconditional bail and their trial has been timetabled to take place on June 21 next year.