Brigadier Saunders was shot four times

On the eve of the first anniversary of the murder, the general's widow, Mrs Heather Saunders, says she is frustrated by the failure to arrest anyone, but she hopes the witness protection measures in the new anti-terrorism law will make a difference.

Mrs Saunders will attend a memorial service in Athens and will lay a wreath at the site where assailants drove by on a motorcycle and shot her husband.

Active investigation

Mihailis Chryssohoidis, the Greek Minister for Public Order, has told the BBC that the investigation is still very active, with the help of British counter-terrorist experts.

He promised Mrs Saunders the killers would be caught.

The N-17 group, which gets its name from the date of a student rebellion in November 1973, is blamed for 23 killings in the past 26 years.

Victims include Greek industrialists, judges and diplomats.

The new anti-terrorist law is designed to give the police greater powers in arresting suspects and it sanctions the use of DNA testing to aid in investigations.