US President Barack Obama has said that Iran is still more than a year away from developing a nuclear weapon.

His comments, in an interview on Israeli television, come ahead of his visit to the Jewish state next week.

Israeli Prime Minister Benjamin Netanyahu previously set a "red line" of spring or summer for when Iran would be close to weapons capability, suggesting prospects for an Israeli attack around that time.

But Iran's latest talks with world powers plus adjustments in Tehran's uranium enrichment processes are widely thought to have pushed back that deadline.

Mr Obama also sought to reassure Israelis that military force remains a US option if sanctions and diplomacy fail to thwart Iran's nuclear ambitions.

Iran denies that is its aim. Its nuclear standoff with the West will be high on the agenda during Mr Obama's first presidential trip to Israel.

He faces a tough challenge of trying to narrow his differences on the matter with the right-wing prime minister.

When asked if he would order an attack on Iran should diplomacy fail, Mr Obama said: "When I say that all options are on the table, all options are on the table.

"The United States obviously has significant capabilities but our goal here is to make sure that Iran does not possess a nuclear weapon that could threaten Israel or could trigger an arms race in the region."

Mr Obama and Mr Netanyahu have had a notoriously fractious relationship.

However, with both leaders starting new terms they have a chance to open a new chapter.

The US President will also try a different tack, using his three-day visit to reach out to a wary Israeli public and try to convince them of his commitment to their security.

The centrepiece will be a nationally televised address to university students in Jerusalem.

Mr Obama will see the Dead Sea scrolls in Jerusalem and a high-tech exhibit in the Israel Museum.

He will lay wreaths at the graves of Theodor Herzl, the founder of modern-day Zionism, and assassinated Prime Minister Yitzhak Rabin and visit Yad Vashem, the memorial to 6m Jews killed in the Nazi Holocaust.

He will also visit the Church of the Nativity in the West Bank town of Bethlehem.