Facing criticism over its human rights record, Kazakhstan won a measure of support from Sarkozy, who said he discussed the issue with President Nursultan Nazarbayev but did not come to "give lessons."
France is among the Western nations courting Kazakhstan, a giant ex-Soviet republic with rich oil and gas resources and a strategic location bordering China and Russia _ long the dominant regional force _ north of Afghanistan.
Nazarbayev said the transit agreement signed Tuesday governs the movement of military hardware and personnel to supply French forces serving with NATO in nearby Afghanistan. Kazakhstan lies between Russia and three smaller Central Asian nations that border Afghanistan.
"We need Kazakhstan to resolve the crisis in Afghanistan and in Iran, and to establish new relations with our friends in Russia in the fight against extremism," Sarkozy said.
In energy, a deal worth an estimated 1 billion euros ($1.46 billion) was signed to formalize the acquisition by French companies Total and GDF Suez of a 25 percent stake in the Khvalynskoye offshore natural gas field project in the Caspian Sea. The field is now being developed by Russian oil giant, Lukoil, and is expected to start operations in 2016 and produce up to 3 trillion cubic feet (9 billion cubic meters) of oil per year.
Kazakhstan also awarded a consortium of French companies a deal to take part in building a crucial $2 billion oil pipeline linking the vast Kashagan oil field to the Caspian. Energy supplies through the route will be transported across the inland sea by tanker to Azerbaijan and westward to Europe, circumventing Russia.
Both Western and Central Asian nations are eager to decrease Russia's control over oil and gas export routes from the region.
"This is an extremely important project that will become the main artery to transport Kazakh oil to Europe," Nazarbayev told reporters.
Other commercial accords included an agreement to create a joint venture between the two countries' state-owned nuclear power companies to produce and marketing fuel for nuclear power plants.
Kazakhstan is on the cusp of becoming the world's largest supplier of uranium, but it has in recent years reached out to commercial partners in Russia, Japan and China in a bid to ensure in can take part in all stages of the nuclear fuel production cycle.
France's Thales signed a 100 million euro ($150 million) contract to supply radios to the Kazakh army that the company hopes will lead to a bigger, 2 billion euro ($3 billion) project to supply communication equipment to the Kazakh military _ a market dominated by Russian suppliers.
"All these deals are in the strategic interests of both our nations," Nazarbayev told a gathering of officials and investors.
Sarkozy's visit came as Kazakhstan has faced mounting criticism over its human rights record ahead of its 2010 chairmanship of the Organization for Security and Cooperation in Europe, a leading trans-Atlantic security and democracy body.
Human Rights Watch said this week that Kazakhstan has repeatedly flouted basic democratic freedoms and has been slow to implement reforms in line with its commitments to the OSCE.
But Sarkozy, the first French leader to visit the former Soviet nation since 1993, mounted a robust defense of Kazakhstan's upcoming chairmanship of the OSCE.
"When you come to this part of the world, you cannot make presuppositions, but you should try understand what is happening," Sarkozy said. "The optimal way of solving problems _ and there are problems, which I have discussed with the president _ is not necessarily to come and give lessons."
Nazarbayev dismissed criticism of his country' rights and democracy record.
"Our main aim is to strengthen our independence, raise our economy, improve people's lives and gradually become closer to the civilized world by adopting all the values of freedom and democracy that exist in the Western world," Nazarbayev said.
(This version CORRECTS that the deal with Total and GDF Suez is worth 1 billion euros, not $1 billion.)