Speaking on his first trip abroad since he and US President Barack Obama were sworn in for a second term in office, Biden told the conference on Saturday that there was still time to resolve the international community's dispute with Tehran through diplomacy.

"The ball is in the government of Iran's court. It is well past time for Iran to adopt a serious good-faith approach to negotiations," Biden said. "Abandon the illicit nuclear program and your support for terrorism and there will be meaningful incentives."

Biden also said Washington was open to holding bilateral talks with Tehran, but that the offer was not unconditional.

"That offer stands, but it must be real," Biden said. "And there has to be an agenda that they are not just prepared to do it for the exercise."

Biden's statement comes just weeks after Iran announced plans to step up its rate of uranium enrichment activities.

Germany's foreign minister urged Tehran to take Washington up on its offer.

"Iran should not wait any longer to take up the willingness Vice President Biden has stressed to hold substantial negotiations on its nuclear program," Guido Westerwelle said.

"From our point of view, announcing an accelerated expansion of uranium enrichment in Iran is the wrong signal," he added.

Highly enriched uranium can be used in the production of nuclear weapons, something the US and other Western nations fear Tehran is aiming to do. Iran has repeatedly insisted that its nuclear program is entirely peaceful and meant solely for producing energy.

Germany is one of six major powers involved in ongoing talks aimed at curbing Iran's suspected nuclear ambitions.

Biden began his speech by stressing the strength of the long-standing diplomatic and military ties between the US and Europe. He said this should be enhanced, including through the creation of a free-trade zone.

"We should pursue a trans-Atlantic partnership, and if we go down that road we should try to do it on one tank of gas and avoid a protracted rounds of negotiations," Biden said. "It would be good for growth and job creation, it would be good on both sides of the Atlantic ... The rewards of success are almost boundless."

No common ground on Syria

The conflict in Syria is another issue that is front and center at the Munich conference, which brings together senior diplomatic and security officials from around the world each year.

Biden used his speech to stress the US position, which is also held by many other nations, that there can be no lasting resolution to the conflict as long as President Bashar Assad clings to power.

"President Assad - a tyrant hellbent on clinging to power - is no longer fit to lead the Syrian people and he must go," Biden said.

Also attending the conference was Foreign Minister Sergei Lavrov of Russia, which has been one of Assad's staunchest supporters in the international community. Differences between the West on the one hand and Russia and China on the other, have made it difficult for the international community to agree on a common approach to the conflict in Syria.

The United Nations-Arab League peace envoy alluded to that problem in his speech.

"I am much more conscious of the difficulties and of the country being broken day after day than I am of a solution around the corner," Brahimi told the conference on Friday.

pfd/mkg (AP, dpa, AFP)