The 25-year gas deal between the National Iranian Gas Export Company (NIGEC) and Switzerland's Elektrizitaetsgesellschaft Laufenburg (EGL) was finalized in September last year. Under the deal, Iran has to deliver 5.5 billion cubic meters of gas per year to Europe via a pipeline scheduled to be complete in 2010.
"Today, we have witnessed the signing of an important gas agreement between companies of the two countries," Manouchehr Mottaki said at a joint news conference with his Swiss counterpart Micheline Calmy-Rey, who is currently on a visit to Iran.
The Swiss minister said the bilateral deal did not violate United Nations sanctions imposed on Iran over its controversial nuclear program and served only to secure uninterrupted energy supplies to her country.
"We have a strategic interest to secure our gas supplies and diversify our gas suppliers," Calmy-Rey said.
She also said the current deal may reduce Europe's dependency on energy supplies from Russia.
"We are decreasing our dependence, and the dependence of Europe, on Russian gas," she said.
Russia's energy giant Gazprom announced last week that the average price for natural gas for Europe in 2008 could reach $400 per 1,000 cubic meters, 13% more than previously expected.