MOSCOW, January 27 - RAPSI. U.S. authorities have toughened prison conditions for Russian businessman Viktor Bout, said deputy Foreign Minister Sergei Ryabkov.

"His prison food has been changed and security has been tightened up. I attribute this in part to the coming sentence announcement on February 8," said Ryabkov on the Echo of Moscow radio.

In Rybkov's view such things affect human psychology, especially when the person is kept in a "high security prison".

Bout was arrested in Thailand in March 2008 during a sting operation led by U.S. agents and extradited to the United States in November 2010 after spending more than two and half years in Thai prisons.

The United States has charged Bout with conspiring to kill Americans and US officials, illegal surface-to-air missile trafficking, and supporting terrorism through cooperation with the Colombian guerilla organization FARC.

Bout has pleaded not guilty to all charges.

The case hearings started in October.