While nuclear negotiations between Iran and the West have yet to yield a final result, the International Atomic Energy Agency (IAEA) chief warns against imposing fresh sanctions on the country.

Speaking on Friday in Berlin, IAEA Director-General Mohamed ElBaradei expressed hope that Iran would agree to an international nuclear fuel proposal, which is said to be aimed at resolving a long-standing dispute over the country's nuclear program.

"We have not received any written response from Iran. What I got of course is an oral response, which basically said 'we need to keep all the material in Iran until we get the fuel,'" ElBaradei said.

"I hope to get an answer soon, within the next week or so," he added.