German Foreign Minister Frank-Walter Steinmeier met with Iran's chief nuclear negotiator Ali Larijani,in surprise talks in Berlin on the eve of the G8 summit. But no progress was made towards resolving the ongoing row over Tehran's nuclear program.

Steinmeier told reporters the aim of the talks had been to create more "suppleness" on the part of Iran and to persuade the Islamic republic to rethink its stance.

Iran has defied international pressure to halt uranium enrichment, saying it wants only to generate energy for a growing population when fossil fuels eventually run out.

The western powers believe that Iran is conducting a nuclear enrichment program with the aim of making a bomb, a charge which Tehran has repeatedly denied.

"It's too late to push us back"

Back in Tehran, Iranian President Mahmoud Ahmadinejad said that it was too late to stop his nation's nuclear program, telling reporters Tuesday, "We have broken through to a new stage and it is too late to push us back."

At a typically defiant news conference, Ahmadinejad also warned the UN Security Council of the dangers of seeking to pressure Iran, telling the world body not to risk playing with a "lion's tail."

"We advise them not to indulge in child's play... They say that Iran is a lion sat down in a corner. And we tell them: Do not play with the lion's tail."

Diplomatic sources in Berlin said Germany was making "efforts to map the way forward on the Iranian nuclear dossier in close consultation with the EU foreign policy coordinator Javier Solana."

Solana and Larijani have met twice in recent weeks but failed to defuse the standoff over Iran's refusal to stop enrichment work. Solana tried to coax Tehran to halt enrichment in exchange for a package of political, economic and trade incentives.

But instead, Tehran's intransigence has led the West to threaten more sanctions against the Islamic republic. The UN Security Council has already agreed to two sets of sanctions against Iran for ignoring its calls to suspend enrichment, and Western powers are now openly talking of a new resolution after Iran missed the latest deadline.

A UN report released last month stated that Tehran could be three to eight years away from developing nuclear arms.

"We are dealing with psychological warfare"

In Jerusalem on Tuesday, Israeli Foreign Minister Tzipi Livni urged the international community not to succumb to Iran's position.

"Iran is trying to convince the world that it has crossed the point of no return in order to weaken the international community's efforts to stop Iran," her office quoted her as saying.

"We are dealing with psychological warfare," said Livni, whose country is considered the sole, undeclared nuclear power in the Middle East.

Meanwhile, Ahmadinejad predicted that Washington would never be able to hurt the Islamic republic even though the US has never ruled out military action to bring Iran to heel over its nuclear drive.

US Secretary of State Condoleezza Rice, in the northeastern German resort of Heiligendamm for the G8 talks said that Ahmadinejad, who has repeatedly called for the destruction of the Jewish state, was "digging a deeper and deeper hole for his country."

The G8 grouping of the US, Britain, Germany, France, Italy, Canada, Japan and Russia have threatened tougher sanctions if Iran fails to meet UN demands to halt enrichment.