Biden, who two years ago introduced the concept of "the reset button" after years of tension under George W. Bush's presidency, told President Dmitry Medvedev that WTO accession was "the most important item on our agenda," in a meeting at the presidential residence in Gorky, a Moscow suburb.

Earlier in the day, Biden used an appearance at a management school to urge Russia to improve its legal system and anti-corruption efforts. But such issues were absent from talks with Medvedev, and the tenor of the meeting indicated this visit is really about business.

The Obama administration regards integrating Russia into the world economy as key to its development and stability, and that has moved concerns about Russian rule of law and democratic backsliding to a lower priority.

Even his call for reform at the Skolkovo management school was cast in economic terms.

"Investors are looking for assurances that the legal system treats them fairly and acts on their concerns swiftly," Biden told a meeting of top Russian and American businessmen at the school, which Russia sees as the core of an ambitious innovation center that officials hope will be Russia's equivalent of Silicon Valley.

Some Russian newspapers have theorized that Biden's trip could be seen as support for Medvedev running for a second term next year. Medvedev is seen as the weaker figure of Russia's ruling tandem, dominated by the more hardline Prime Minister Vladimir Putin, and it is as yet uncertain whether Medvedev will seek a second term or cede his candidacy to Putin, who was president in 2000-2008.