Diplomats at the Austrian Embassy pledged this week to explain the “tragic” situation of British mother Beth Alexander to guests of an event commemorating the Anschluss.

The 75th anniversary of the Anschluss — Nazi Germany’s annexation of Austria in 1938 — was due to be marked at the London embassy in a joint event with the Association of Jewish Refugees on Wednesday.

Supporters of Ms Alexander, who has lost custody of her three-year-old twin sons, Benjamin and Samuel, to their Austrian father Michael Schlesinger, were due to protest at the event to raise awareness of her case and give a petition to the embassy.

Christoph Weidinger, deputy Austrian ambassador, speaking before the event, said: “We can imagine the immense grief and suffering the mother must be enduring.” He said the embassy would pass the petition on to the Viennese authorities.

Adrian Alexander, one of Beth’s brothers, who is organising the protest, said: “We appeal to the Austrian government to make sure justice is done and seen to be done. The twins are too young to speak, so we will speak for them”.

Further protests are planned in Israel and New York, which Mr Alexander explained was to reinforce the international nature of the campaign.

Ms Alexander and Dr Schlesinger are involved in a protracted custody dispute in a Vienna court, which is currently suspended pending investigation of two judges for acting improperly.