Russia denied on Friday that it was waging a trade war with Ukraine to discourage its ex-Soviet neighbour from establishing closer political and economic relations with the European Union.
The Ukrainian Employers' Federation reported on Wednesday that all goods destined for Russia were being held up at the border without an explanation and subjected to rigorous checks.
The claim -- supported by such Ukrainian giants as the mining firm Metinvest and the beer maker Obolon -- follows the suspension in July of Russian imports from the popular chocolate brand Roshen over alleged quality concerns.
The head of Russia's consumer rights protection agency confirmed on Friday that Ukrainian goods were being put to more exacting inspections but denied any link to politics.
"We have a long and specific list of complaints ... relating to the protection of consumer rights," Federal Service for the Oversight of Consumer Protection and Welfare chief Gennady Onishchenko was quoted as saying by Interfax.
"If you want to call this a trade war, then call it a trade war," he added. "But we are conducting professional work."
Russia remains Ukraine's closest trade partner and is responsible for nearly a quarter of its total exports.
But the authorities in Kiev are keen to reverse that dependence and have been leading negotiations with Brussels over a trade agreement that could serve as a stepping stone for Ukraine's eventual membership in the 28-nation bloc.
Ukrainian Prime Minister Mykola Azarov acknowledged "difficulties" at the border on Thursday but urged the media not to play up the scale of the dispute.
"Do not inflate these problems artificially," Azarov cautioned.
Ukraine was due to raise the issue later on Friday during a meeting in the Russian city of Suzdal of a commission overseeing trade in the Moscow-led Customs Union that also groups Belarus and Kazakhstan.
Russian officials have said that Ukrainian goods would pass the border more smoothly if Kiev agreed to join the union -- something that Ukrainian President Viktor Yanukovych has thus far refused to do.
Nationalist politicians in Ukraine who support closer European integration accuse Moscow of trying to force Kiev into the Russian bloc by imposing the trade restrictions.
There were initial signs on Friday of Ukraine being prepared to take countermeasures that included its own bans on imports from Russia.
Kiev's Segodnya daily said Yanukovych had ordered his National Security and Defence Council to convene an emergency meeting focused on reciprocal measures Ukraine could take against Russia.
Segodnya added that Ukraine was banning the import of grain from some Russian regions in Siberia and the North Caucasus owing to fears over the spread of foot and mouth disease.
The Russian consumer rights protection agency chief said on Friday after a meeting in Moscow with Ukraine's agriculture minister that no "breakthrough" was achieved at the talks.
Onishchenko added that that two sides had agreed for Russia to conduct checks of four Roshen factories in Ukraine that could potentially lead to an end of restrictions against the chocolate maker.
Russia has been frequently accused of using trade restrictions as a political weapon against ex-Soviet countries with pro-Western leanings and has previously cut supplies of gas to Ukraine.
But some analysts said the latest measures were far more drastic that those previously imposed on Ukraine or Georgia and Moldova -- two countries that have long been seeking closer ties with Europe and the United States.
"Even the 2006 bans that Russia imposed on Georgian and Moldovan wine, juice and mineral water does not compare to the current Russian-Ukrainian trade war," Moscow's Higher School of Economics professor Alexei Portansky wrote in the Russian online edition of Forbes.
"Those bans covered a specific range of products," Portansky noted. "Plus, Russia had at that point not been a member of the World Trade Organization and was not bound by the generally-accepted intentional rules and norms."