Minsk, June 6 - Russia has banned the import of 500 types of milk product from Belarus, Russian news agencies reported on Saturday, at a time of strain between the two former Soviet republics.
Russian media cited a top health official, Gennady Onishchenko, as saying the products had failed health standards. But Belarus denied this, calling the move a "warning signal".
Russia, which has in the past imposed trade restrictions at times when it was at odds with other ex-communist countries, has recently grown alarmed by Belarus's tentative rapprochement with the European Union.
"The ban is in force as of today," media cited Onishchenko as saying. "I warned Belarus. But a month has passed and there has been no fundamental change."
Belarus earns billions of dollars from its dairy exports, and last year had about 4 percent of the Russian market.
A Belarussian government source told Reuters the products that were banned had in any case not been cleared for export to Russia.
"That's why it is difficult to understand why these products were banned in such as loud and demonstrative way," he said, declining to name the products.
A Belarussian official told a television station that the ban had been imposed without the necessary tests, and called it a "warning signal".
Russia has in the past banned meat products from Poland, wine from Moldova and mineral water from Georgia when political tensions with these countries were high.
Last week it delayed giving Belarus a $500 million loan on grounds that Belarus could be insolvent by the end of the year, prompting an angry response from President Alexander Lukashenko.
A row with Russia over gas supplies at the end of 2006 was a prelude to Lukashenko, long accused by the West of repressing dissent, muzzling the media and rigging his re-election, taking steps towards a reconciliation with the EU.
The EU suspended a travel ban on Lukashenko, who travelled to Italy in April and met Pope Benedict, his first visit to Western Europe in years.
"Of course, this is not a question of microbes or certificates, but a question of politics," said Yaroslav Romanchuk, director of the Mises think tank in Belarus.
"That is clear, and no one is really hiding the fact that this was caused by the political conflict that we have seen recently between the Russian and Belarussian authorities."