The United States is ready for direct talks with Iran on its nuclear program if it is serious about negotiations, Vice President Joe Biden said Saturday.

Speaking at a security conference in Munich, Biden said Iran, which says it is enriching uranium for peaceful energy only, now faced "the most robust sanctions in history" meant to ensure it does not develop nuclear weapons, Reuters reported.

"But we have also made clear that Iran's leaders need not sentence their people to economic deprivation and international isolation," Biden said. "There is still time, there is still space for diplomacy backed by pressure to succeed. The ball is in the government of Iran's court."

Iran's foreign minister Sunday welcomed Biden's comments, NPR reported.

"We have no red line for bilateral negotiations when it comes to negotiating over a particular subject," Ali Akbar Salehi said at the Munich conference. "If the subject is the nuclear file, yes, we are ready for negotiations but we have to make sure ... that the other side this time comes with authentic intention, with a fair and real intention to resolve the issue."

Salehi also announced that talks with the so-called P5+1 -- the five members of the UN Security Council and Germany – will resume Feb. 25 in Kazakhstan, CNN reported.

Asked whether Washington might consider direct talks with Iran to smooth the process, Biden said, "When the Iranian leadership, Supreme Leader [Ayatollah Ali Khamenei], is serious.

"We have made it clear at the outset that we would be prepared to meet bilaterally with the Iranian leadership, we would not make it a secret that we were doing that, we would let our partners know if that occasion presented itself.

"That offer stands, but it must be real and tangible and there has to be an agenda that they are prepared to speak to. We are not just prepared to do it for the exercise."

Russian Foreign Minister Sergey Lavrov said he “would strongly support what Vice President Biden said about the need for incentives to be clearly shown to Iran,” the Associated Press reported.

“We have to convince Iran that it is not about the regime change,” he said.

Speaking at a news conference in Munich, Sen. John McCain, R-Ariz., said he would have no objection to direct talks but questioned how much these would achieve if fundamental questions over Iran's nuclear program remained unresolved, Reuters reported.

"I don't know when we will have direct talks between the United States and Iran. That is a subject for the president of the United States. I don't think anyone here objects to that," he said. But he added, "to have grounds for optimism, I think, would be a mistake."