Brussels  - The European Union is preparing to implement a tougher United Nations sanctions against Iran despite ongoing efforts at resolving the nuclear conflict with the Middle Eastern country, said EU foreign policy chief Javier Solana on Tuesday.

"The EU has a responsibility to implement resolution 1803 of the UN Security Council," Solana said after talks with EU foreign ministers in Brussels.

Solana further called upon the government in Tehran to respond "constructively" to a four-week-old offer by the five permanent members of the UN Security Council plus Germany.

"I am optimistic that there will be a constructive answer," Solana said.

On behalf of the five United Nations Security Council veto powers and Germany, Solana met with Iranian negotiator Saeid Jalili to talk about future economic, political and nuclear energy cooperation, once Tehran halted its nuclear activities. (dpa)