MUNICH — U.S. Vice President Joe Biden on Saturday offered Iran direct talks to end its nuclear program and said Syrian “tyrant” Bashar al-Assad must step down.

UN-Arab League envoy Lakhdar Brahimi, however, said he had little hope of a quick end to the conflict that has claimed 60,000 lives, while Russia reiterated its support for key ally al-Assad.

Syria, Iran, Mali and other global trouble spots were the focus of the Munich Security Conference, where much debate but few concrete results were expected on the world’s top security challenges.

Biden used the annual event for his first address abroad since President Barack Obama started his second term, and ahead of Obama’s State of the Union address next week.

One US strategic priority was “maintaining our commitment to the elusive _ elusive but essential _ goal of Middle East peace” and of strengthening democracies, he said.

Biden reiterated a US offer to Iran of bilateral talks on ending its nuclear program, which the West suspects is aimed at building a bomb, a charge the Islamic republic denies.

“There is still time, there is still space for diplomacy to succeed,” Biden said. “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.”

Asked about the specifics of his offer, Biden said: “We would be prepared to meet bilaterally with the Iranian leadership . . . . That offer stands, but it must be real.”

He said there needs to be a clear agenda as Washington is “not prepared to do it just for the exercise.”

The US offer for direct diplomacy was backed by EU foreign affairs chief Catherine Ashton and German Foreign Minister Guido Westerwelle, who urged Iran to “take the extended hand.”

Iran’s Foreign Minister Ali-Akbar Salehi was scheduled to speak at the conference on Sunday, as was Israeli Defense Minister Ehud Barak.

On Syria’s bloody conflict, in its 22nd month, Biden said al-Assad “is no longer fit to lead the Syrian people, and he must go.”

But Russian Foreign Minister Sergei Lavrov reiterated the Kremlin’s support for its ally, action against whom Moscow and Beijing have blocked in the UN Security Council.

Lavrov cautioned that “we should avoid a forceful intervention, especially without a mandate from the UN Security Council” and also spoke out against “arbitrary sanctions” against Damascus.

Asked about the risk of the regime using unconventional weapons, Lavrov said “the greatest danger is the possibility that the chemical weapons will fall into the rebels’ hands.”

Biden said the United States is looking for areas of cooperation with Russia but also pointed to “serious differences on issues like Syria, missile defence, NATO enlargement, democracy, human rights.”

On Syria, Brahimi told the conference late Friday: “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.”

Moaz Al-Khatib, head of the National Coalition of Syrian Revolutionary and Opposition Forces, reiterated a willingness to negotiate with Damascus to end the killing.

But if talks don’t work, he said, he would like Western military support against the regime, which he accused of massacres, atrocities and sexual crimes.

Al-Khatib said: “It is just not acceptable for the international community to be a bystander, just watching what’s happening to the Syrian people.”

The other conflict that occupied the 400-strong conference was Mali, where French forces intervened three weeks ago to stop an advance on the capital by al-Qaida-linked militants.

French President Francois Hollande visited troops in Mali on Saturday and said the operation against Islamist rebels was not yet over.

Germany, which has offered some logistical support in Mali, will send 40 military trainers, said Defense Minister Thomas de Maiziere, to help modernize Mali’s military.

NATO chief Anders Fogh Rasmussen said, in view of emerging security threats, the alliance must ready for more missions as it prepares to end combat operations in Afghanistan by 2014.

“When I look at our world, I see an arc of crises stretching from the Sahel to Central Asia,” Rasmussen said.

“This does not mean we will have to intervene everywhere, nor that we are set for confrontation. But it does mean we must stand ready to deter, and defend against, any threat.”

He also appealed to cash-strapped NATO members not to cut funds to the US-European alliance, saying “security challenges won’t wait while we fix our finances.”

About 1,000 peace activists demonstrated without incident outside the Munich conference venue, which has been guarded by 3,400 police deployed for the three-day event.

• Frank Zeller, Associated Press