Russia government voiced an ultimatum several hours ahead the G20 Summit.

Moscow has warned the U.S. Administration that replacement of Jackson-Vanik Ammendment with Magnitsky blacklist is 'unacceptable', Russian Presidential Aide Yuri Ushakov said on Sunday, - RIA Novosti reported.

A group of influential U.S. senators, including former Republican presidential candidate, John McCain, proposed in mid-March to introduce a blacklist of Russian officials allegedly linked to Hermitage Capital lawyer Magnitsky's death, in a Moscow pre-trial detention center in November 2009, in exchange for the cancellation of the Jackson-Vanik amendment.

The amendment limits trade with Russia and is an obstacle to the application of World Trade Organization (WTO) rules between the two countries. The restrictions imposed by Jackson-Vanik are often waived, but remain in place and are a thorn in the side of Russia-U.S. trade relations.

"We've warned the U.S. administration that replacement of Jackson-Vanik with Magnitsky bill is unacceptable," Ushakov said ahead of a meeting between the Russian president and his U.S. colleague.

The projected Magnitsky bill is an ostentatious anti-Russian move and if this bill is passed Russia will introduce retaliatory measures, Ushakov continued.

"Many countries... deny entry to undesirable persons. This is done not publicly and is a common diplomatic practice. But now the issue is about an ostentatious anti-Russian move, they [the congress] are trying to assign an expanded value to the bill, first of all, to use this law when the U.S. is dissatisfied with Russia," Ushakov said.

"Everybody understands that it [the Magnitsky blacklist] is a negative element in the bilateral ties. Everybody understands that retaliatory Russian measures would be inevitable, but we would like to avoid them," he added.

Magnitsky was arrested on tax evasion charges in November 2008, just days after accusing police investigators in a $230 million tax refund fraud, and died after almost a year in the Matrosskaya Tishina pre-trial detention center in Moscow.