Israel's defence minister said Thursday that the Jewish state and its US ally should be prepared to use "all means" to prevent Iran from obtaining a nuclear weapons capability.

"I believe that it should be in the first priority of each of us to deal with this threat by all means, in all fields," Moshe Yaalon said at joint news conference with visiting US Defence Secretary Chuck Hagel.

The Pentagon chief's visit came as the United States and other major powers pressed talks with Iran on a long-term agreement to allay international concerns about its nuclear ambitions.

Israel has strongly opposed the negotiations with its arch-enemy, and has said repeatedly that it is prepared to go it alone if necessary with pre-emptive military action against Iran's nuclear facilities.

"I believe the United States and Israel share the same goal -- not to allow a military nuclear Iran," Yaalon said.

"We might have differences, even disputes regarding how to get it but we have the open channels, the secretary of defence and myself.

"The bottom line is that Israel should be ready to defend itself, by itself."

Hagel said the negotiations between the powers and Iran were not open-ended -- the parties are working to a July 20 target for an agreement.

He said Washington was continuing to cooperate closely with its Israeli ally on the Iran issue, even while the negotiations continued.

"Because we're on a diplomatic track... does not preclude all of the other security and defence measures that we continue to pursue outside that diplomatic track, including this relationship with Israel," he said.

Hagel was on the last leg of a Middle East visit which also took him to Saudi Arabia, which has its own concerns about the nuclear talks with its regional rival.

Hagel and Yaalon both played down recent reports of extensive spying by Israel on its US ally.

"As former head of intelligence, I wasn't allowed to spy in the United States whatsoever. And as defence minister I don't allow to spy in the United States whatsoever," Yaalon responded, speaking in English to a question about the reports.

Hagel said: "I have heard of that report. I'm not aware of any facts that would substantiate the report."

Newsweek magazine alleged in a report last week that Israel spies on the United States more than any US other ally does, and that such activities have reached an alarming level.