Aachen, Germany - The murder trial of a former Nazi SS trooper was postponed on Tuesday because the hard-of-hearing defendant was struggling to follow proceedings.

Heinrich Boere, 88, is on trial in the town of Aachen, accused of killing three civilians in German-occupied Netherlands during World War II.

Presiding judge Gerd Nohl said the case would only continue once Boere was equipped with a hearing aid, in response to a request by his lawyers.

The defence was criticized for trying to delay the trial, after Boere's hearing problems cropped up unexpectedly. Asked the previous day whether he had been able to hear the charges read against him, Boere had answered, "No."

A doctor certified that the defendant suffered from an inner-ear problem, which meant he could not differentiate between all vowels.

Boere was originally sentenced to death in absentia by a Dutch court in 1949 for the killings. The sentence was later commuted to life imprisonment, but Boere escaped prison by fleeing to Germany.

A German court then charged Boere with the killings in April 2008, but his lawyer argued that he could not be tried for the same crime twice.

Boere is sixth on a list of the 10 most wanted Nazi war criminals issued by the Simon Wiesenthal Centre in Jerusalem.

Top of the list is John Demjanjuk, who is to go on trial in Germany next month accused of involvement in mass murder of Jews in the Nazi death camp at Sobibor in German-occupied Poland. (dpa)