VIENNA (Reuters) - Austrian prosecutors said on Thursday they are investigating former far-right leader Heinz-Christian Strache and others on suspicion of breach of trust in connection with a sting video that forced Strache to quit the coalition government.

FILE PHOTO: Austrian Vice Chancellor Heinz-Christian Strache reacts as he addresses the media in Vienna, Austria, May 18, 2019. REUTERS/Leonhard Foeger/File Photo - RC1AB4E44170

Strache stepped down as Austrian vice chancellor and head of the far-right Freedom Party (FPO) on May 18 after German media published secretly filmed footage from a 2017 dinner party at which Strache met a woman posing as a Russian oligarch’s niece.

In the footage, Strache appears to offer to fix state contracts in return for political or financial help. He has acknowledged the video was “catastrophic” but says he did nothing illegal and did not follow through on his comments.

Strache’s lawyer was not immediately available for comment on Thursday.

A spokesman for a prosecutors’ office responsible for economic crimes and corruption said on Thursday it was investigating Strache as well as Johann Gudenus, a former FPO local lawmaker in Vienna who also featured in the video.

The spokesman said the investigation was into suspected breach of trust in connection with the sting video footage, and was also against persons unknown.

Vienna prosecutors had previously said they were investigating “in multiple directions” in relation to the footage.

The origins of the video have remained a mystery in Austria, but the political damage from the sting has been great. Conservative Chancellor Sebastian Kurz called off his coalition with the FPO the day Strache stepped down.

Kurz tried to stay on but parliament dismissed him and his cabinet, saying he deserved at least some of the blame for a scandal stemming from a far-right party he brought to power.

Kurz hopes to return to office after a parliamentary election widely expected to be held on Sept. 29.

Strache has been replaced as FPO leader but he could yet become a member of the European Parliament thanks to Austria’s electoral system, under which voters pick a party list and a favorite candidate on that list.

Although he was 42nd and last on the FPO list for the May 26 European election, enough FPO voters picked Strache as their preferred candidate for him to be entitled to one of the party’s three European parliament seats. He has kept Austria guessing on whether he will take it up.