Shortly after Sarkozy spoke at the Group of Eight summit in Japan, his foreign ministry said Tehran had not undertaken to suspend sensitive nuclear activities under the terms of a deal offered to it by six nations.
"The group of six nations plan to send Mr Solana (to Iran) for in-depth discussions on the differences between their latest proposals and the ones that were already on the table," Sarkozy said in Toyako in northern Japan.
"When we have the results, each country will try through its own channels to find out more about the intentions of the Iranian regime," he said.
The group of six nations -- Britain, China, France, Germany, Russia and the United States -- last month offered Tehran a package of technological and economic incentives in return for Iran suspending its uranium enrichment activities that the West fears could be used to make an atomic bomb.
Iran had in May proposed a deal to the six nations, which resulted in last month's counter-offer aimed at easing fears over Iran's nuclear ambitions.
Tehran responded to that offer Friday in a letter that has not been made public, but President Mahmoud Ahmadinejad has repeatedly insisted that Iran will not give up its right to a nuclear programme.
Solana's new mission to Iran is aimed at reconciling Iran's two submissions to the group of six, which it has said are aimed at settling the tensions of what it insists is the use of nuclear technology for peaceful purposes.
But Solana's spokeswoman Cristina Gallac told AFP that his office was "in the process of preparing a possible meeting with (Iranian negotiator) Said Jalili in the coming weeks".
"We have not yet set a date or a time," she said
Shortly after Sarkozy announced Solana's mission, France's foreign ministry revealed that the Islamic state had not undertaken to suspend sensitive nuclear activities.
"The fact that there is no mention of suspending sensitive activities is clearly an issue," foreign ministry spokesman Eric Chevallier said in Paris.
G8 leaders were expected to discuss the Iranian nuclear standoff during their summit in Japan that ends Wednesday.