Miller is accompanying Russian President Dmitry Medvedev who is on an official visit to Spain.
"Up until now, Gazprom has not supplied natural gas to Spain, In accordance with this agreement, gas under Gazprom contracts will appear on the market of that country in the near future," Miller said.
The Gazprom CEO said that initially the volumes of gas involved would be insignificant.
"But in accordance with the agreement, Spain will in the future receive liquefied natural gas from the Shtokman gas field, which will be put into operation in 2014," Miller said.
The project to develop the Arctic gas field, with estimated reserves of 3.8 trillion cubic meters, is intended to supply the Nord Stream gas pipeline from Russia to Germany currently being built under the Baltic Sea. The Shtokman project costs are estimated at $30 billion.
Gazprom has a 51% stake in the project, while France's Total and Norway's StatoilHydro have 25% and 24%, respectively.
The first piped gas deliveries from the Shtokman field will begin in late 2013 with liquefied gas supplies in 2014. The project's first phase is expected to produce a total of 23.7 billion cubic meters of gas annually.
Gazprom is considering inviting Spanish companies, in particular, Repsol, to join projects to produce and liquefy natural gas in Russia, Miller said. "We are considering the possibility of our Spanish colleagues working in Russia in the future. In the first place, this concerns the Yamal liquefied natural gas project [in Russia's Arctic]," Miller said.
The CEO said Gazprom may make an investment decision on this issue in the near future.