Russia on Monday imposed a ban on Australian beef byproducts such as offal over the use of a growth stimulant allowed in some nations but that Moscow considers unsafe. The temporary restrictions also affect Belarus and Kazakhstan -- two ex-Soviet nations that are part of a Moscow-led Customs Union. Australia is the world's third-largest exporter of beef after the United States and Brazil. It reported shipping 30,000 tonnes of beef to Russia in 2013. The Interfax news agency said Australia had sent 13,000 tonnes of beef byproducts to ex-Soviet countries in the first 10 months of last year -- most of them to Russia -- worth $21.3 million. Russia's agriculture watchdog Rosselkhoznadzor said the ban was imposed after the discovery of the growth stimulant trenbolone "in several shipments" of Australian beef byproducts. Rosselkhoznadzor chief Sergei Dankvert told Interfax that the ban applied to beef byproducts because they accumulate the steroid in greater quantities than regular meat. Russia has frequently imposed temporary bans on meat products over the use of hormones that are allowed in nations such as the United States but restricted by Moscow's more stringent regulations.