Israeli Prime Minister Benjamin Netanyahu said on Monday that his country's air force is "in control of the skies over Teheran".

Netanyahu made the remarks as he visited the Tel Nof airbase in central Israel with his Defense Minister Israel Katz and Chief of Staff Lieutenant-General Eyal Zamir, according to the Israeli media.

"We are on our way to achieving our two objectives: eliminating the nuclear threat and eliminating the missile threat," he said.

Netanyahu also threatened the citizens of Teheran, telling them to leave the Iranian capital, adding "we are taking action".

Later on Monday The Times of Israel newspaper quoted an unnamed official as saying that Israeli operations against Iran could take two to three weeks, and the timeframe depends on decisions made on the scope of the campaign.

"There's a bank of military targets that we can complete pretty quickly," the source was quoted as saying. "If they decide to expand it to more like government symbols, economical targets, all that, then it will take longer."

A tighter nuclear agreement between Iran and Western powers is the goal, added the official.

Israel is aiming to "cause enough damage" to the nuclear program to revert to diplomacy and "get a good agreement".

However, Israeli attacks on Iran's atomic energy, oil and gas facilities have caused widespread concerns.

Last Friday Israel attacked Iran's Natanz nuclear facility, with above-ground buildings destroyed. Offsite radiation levels appear to be normal, according to the International Atomic Energy Agency, or IAEA.

But the IAEA says that underneath the halls and chambers of the facility, it expects there to be some kind of radiological or chemical contamination in the form of vapors or gases.

There are also assessments of what has been going on at Isfahan and Fordow nuclear sites, which, like Natanz, were also attacked by Israel.

IAEA Director-General Rafael Mariano Grossi has said they should not be attacked at all, as one of the main core responsibilities of the IAEA is to safeguard nuclear security.