Russia opposes crippling sanctions against Iran over its controversial nuclear program, the Interfax news agency reported on Friday, citing Russian Deputy Foreign Minister Sergei Ryabkov.

"The term 'crippling sanctions' on Iran is totally unacceptable to us. The sanctions should aim at strengthening the regime of non-proliferation," Ryabkov was quoted as saying by Interfax.

"We certainly cannot talk about sanctions that could be interpreted as punishment on the whole country and its people for some actions or inactions," Ryabkov said.

He said Russia's position on the Iranian nuclear problem remained unchanged. "We have always favored the resolution of problems regarding the Iranian nuclear program through dialogue and, if possible, interaction with Iran," he said.

Israeli Prime Minister Benjamin Netanyahu, who paid a visit to Russia earlier this week, said "crippling sanctions" must be imposed immediately against Iran's energy sector.

Ryabkov also said Russia would honor a contract to deliver the S-300 air defense systems to Iran and cautioned against politicizing the deal.

"There is a contract to supply these systems to Iran and we will fulfil it. The delays are linked to technical problems with adjusting these systems," he said.

Iran struck an agreement with Russia on buying S-300 systems several years ago, but Russia has delayed the supply of the anti- aircraft missiles.

The S-300 defense system is an advanced mobile system that can travel at more than 2 km per second and shoot down aircraft and cruise missiles from up to 150 km away.

The United States and Israel were trying to persuade Russia not to sell the missile system to Iran because it could foil attempts to hit the country's nuclear facilities with an airstrike.

Ryabkov also said that the U.S. plans to deploy elements of a missile defense system in Romania and possibly in Bulgaria were stalling talks on a successor to the 1991 Strategic Arms Reduction Treaty (START-1) that expired on Dec. 5.

The revamped U.S. missile shield plans are "influencing Russian- U.S. talks on a new arms reduction deal in the most direct way," he said.

Romania has angered Russia earlier this month by announcing it wants to take part in the U.S. missile defense system. News that Sofia was also ready to be part of the U.S. missile shield further raised concerns in Moscow.