Taschler has been accused of arranging a meeting between his son Daniel, a member of the Italian biathlon team, and disgraced doctor Michele Ferrari - the former supplier of cyclist Lance Armstrong - in order to acquire performance enhancing drugs.

Details of the case emerged in 2014 following investigations by prosecutors in Padua and Bolzano.

Gottlieb, a former biathlete himself, who won an Olympic bronze medal in the 4x7.5 killometres at Calgary 1988, denies the allegations, but announced in December 2014 stepping down from his IBU post temporarily until the inquiry was completed.

Daniel Taschler was banned for two years in June 2016.

He was a member of the Italian B-squad when the inquiry surfaced and it is alleged that Ferrari helped him take micro-doses of banned product erythropoietin in 2010 and 2011. 

His 55-year-old father has not been formally found guilty but the IBU has decided to extend its suspension while they investigate the case. 

"All athletes deserve that we avoid having any shadow on their performance and that they can compete without any doubts and can completely concentrate on their sport activities," the IBU said in a statement.

"Nevertheless suspicion is not enough to implement the sanctions and we will keep going down a professional pathway, considering all opinions, but not acting on suspicion only.

"Correctness of Rules has to work both ways - for the guilty and for the non-guilty.

"The IBU will keep the public informed on further steps."

The IBU is also investigating 31 Russian athletes in connection with an inquiry into the manipulation and tampering of drugs samples at events including the 2014 Winter Olympic Games in Sochi.

Provisional suspensions have now been introduced against two unnamed athletes "as a consequence of the opening of IOC (International Olympic Committee) Disciplinary Proceedings".