Oszmann has had a long relationship with the organisation having been involved with the BBU since 2007.

He served as a Board member for seven years and was elected as chairman in 2011, holding the role for five years before confirming he would stand down to enjoy his retirement.

The BBU, which presides over the sport of biathlon in Britain, has confirmed it hopes to have installed Oszmann's replacement by the end of next month.

"The Board, members and athletes are most grateful for all his support, hard-work and enthusiasm during this period," a BBU statement read.

"André is involved with a number of other activities and is no longer able to devote sufficient time to Biathlon. 

"We wish him and his wife Julie, who was instrumental in setting up the BBU Lottery, every successs in the future, and once again, thanks for the past."

Oszmann has overseen a difficult period in charge of the BBU after it was revealed in 2013 that they had no money to operate for the 2014 to 2015 season.

The BBU claimed they had not been funded by UK Sport, Britain's high-performance agency, since 2006.

Their future was secured the month before the 2014 Winter Olympic Games in Sochi, where Britain sent two biathletes - Lee-Steve Jackson and Amanda Lightfoot - when the BBU signed an agreement with Birmingham-based healthcare supplier Aspen Healthcare Solutions.

The deal with the company was worth £250,000 ($327,000/€289,000) over a four-year period and Oszmann claimed the money gave them a "real chance" of developing the sport in Britain.

The BBU's previous sponsor, financial services company Skandia, ended their association with the governing body after Vancouver 2010.