The European Union has filed a formal complaint against Russia at the WTO over Moscow's embargo on pork from the bloc, trade sources said Friday.
The move followed a failure to settle the issue in direct talks in April and May, and comes amid a raft of trade disputes between the two sides.
In January, Russia banned imports of live pigs and pork from the EU after the discovery of two cases of African Swine Fever among wild boar in Poland and Lithuania.
The disease can be deadly for domestic pigs, thereby battering countries' livestock sectors.
While members of the 160-economy World Trade Organisation are allowed to restrict trade on health grounds, Brussels maintains that the ban is totally misplaced.
Critics say Moscow's quality concerns are a figleaf for a political move against ex-communist EU members such as Poland and Lithuania that refuse to toe their Soviet-era master's line.
Both are key players in European pork sector dominated by Denmark, Germany and The Netherlands, for which Russia has long been a major market worth an annual 1.4 billion euros ($1.9 billion).
Brussels says its sector is losing four million euros ($5.4 million) a day because of the ban.
The EU accuses Russia of acting disproportionately and of trade discrimination, noting that imports from Moscow's ally Belarus are not banned even though that ex-Soviet republic has also seen cases of African Swine Fever.
Since joining the WTO in 2012, Russia has also slapped bans on dairy products, chocolates and wine from various ex-communist countries -- including non-EU members Moldova and Ukraine, as well as Poland and Lithuania.
Brussels has already asked the WTO to rule on Russia's "recycling fee" imposed on cars, trucks, buses and other vehicles, which applies only to imports not domestic-made models.
Moscow, in turn, has challenged EU measures against its steel and fertiliser makers under "energy adjustment" tariffs, in force since 2002.
Brussels says the measures are illegitimate because Russia companies benefit from subsidised energy rates, giving them an unfair trading advantage.
But Russia argues that the tariffs have been applied unfairly, making it impossible for Russian companies to export to EU markets, causing annual losses of hundreds of millions of dollars.
Russia has also hit the EU with a WTO complaint over energy market reforms which it says hurt its gas giant Gazprom.
The WTO polices global trade accords in an effort to offer its member economies a level playing field.
It disputes process can last for years, amid appeals, counter-appeals and compliance assessments.
Its panels of independent trade and legal experts can authorise retaliatory trade measures by the wronged party.