"The presidential decree authorizing the extension of counter-measures has been signed. It has a list of goods under embargo [including food products] as an attachment, which has been formalized by the government and will be made public soon," Peskov told reporters in Moscow.
Peskov stressed that the extension of counter-sanctions for a year had been determined by Russia's economic interests.
The extension will come into force on August 6, the spokesman added.
In 2014, Russia introduced a one-year import ban on selected food products from the European Union, the United States and their allies, that earlier imposed sectoral economic sanctions on Russia, accusing it of interfering in Ukrainian crisis.
The list of banned products included meat, poultry, fish, seafood, dairy products, fruit and vegetables.
On Tuesday, Russian Minister of Agriculture Alexander Tkachev said the list of embargoed goods would not be significantly expanded.