A prominent businessman has boasted of how Australia's white race will become extinct in 40 years because the country's men have a declining sperm count.

Mohamed El-Mouelhy, the boss of a halal certification firm, said Australian women would "need us to fertilise them and keep them surrounded by Muslim babies".

In the provocative Facebook post to his followers on Wednesday (26 July), he went on to say that "beer swilling, cigarette smoking, drug injecting [Australians] can only dream of what Muslim men are capable of".

The businessman, who is the head of Halal Certification Authority, one of Australia's largest certifiers, added: "If the country is left to the bigots the white race will be extinct in another 40 years. Muslims have a duty to make your women happy because you are declining, better go chose a plot for youself [sic] at your local cemetery.

"If you can't afford it, commit suicide it is a cheaper alternative for bigots."

It is not certain whether the businessman truly meant the comments or intended them as a joke in the hope they would rile up his anti-Islam opponents.

El-Mouelhy also referred to research published this week by the Hebrew University of Jerusalem that showed a 52% drop between 1973 and 2011 in the average sperm count of men from western countries, including Australia.

No such trends were seen for men in other countries, although the authors of the research warned fewer studies have been carried out in those populations.

The causes of the decline remain unclear but low sperm count has in the past been linked to body weight, lack of physical activity, smoking, stress and exposure to chemicals.

This would suggest measuring sperm quality could be an indicator of broader health trends in the population.

Despite the research, El-Mouelhy's vitriolic post was branded "bigoted" by one user.

It came just days after El-Mouelhy took to Facebook to predict that the popularity of halal food in Australia was "increasing in leaps and bounds" and that Australians – including non-Muslims – will be eating it "more than ever".

The country's 2016 census revealed that Muslims make up 2.6% of the Australian population – up from 2.2% in 2011.

It also showed that Islam has now overtaken Buddhism as the country's most popular non-Christian religion.