Austria said on Tuesday anti-terrorist agents had broken a coded message in a bomb threat issued by suspected rightwing extremists, and linked the group to the murder of four gypsy men last year. Interior Minister Caspar Einem said Austria's anti-terrorist force and military security agency had deciphered 15 pages crammed with numbers sent by the so-called Bajuwarian Liberation Army (BLA).The BLA posted a letter to a current affairs magazine last week, containinga threat to blow up eight prominent people in Austria and abroad aswell as the encrypted message.``The style and format of the message bears the hallmarks of those suspected of having sent letter bombs in the past,`` Einem told Austrian television. The extremists have claimed responsibility for five waves of letter bombs that have hit Austria since December 1993, injuring11 people. All the victims were immigrants or figures linked to foreigner issues. Einem's comments for the first time linked the group to the murder of four gypsies in the southeastern town of Oberwart in February1995. The four men were killed instantly by a booby-trapped bomb while trying to remove a racist sign from their village bearing the words ``Romas (gypsies) back to India.``Einem said a second bomb attack the day after the Oberwart blast in the town of Stinatz, inhabited largely by ethnic Croat immigrants, also appeared to be the work of the group. One man was injured in that attack. He said the coded text contained no further bomb threats but included offensive remarks against a number of politicians and journalists. Police had been in contact with those named in the codes.The threat came in the middle of campaigning for European parliamentary and Vienna state elections next Sunday. Chancellor Franz Vranitzky was one of the eight targets referred toin the original letter. Security around the chancellor has since beentightened. Austria's security chief Michael Sika said on Monday police were tailing 10 suspects following the BLA's latest threat. Police believe the BLA could be a neo-Nazi organisation but other officials say the group may be made up of middle-aged men obsessed with reuniting German-speaking peoples in Bavaria, the Alps and the Danube River.