Israeli Prime Minister Benjamin Netanyahu was hospitalised on Saturday after feeling "dizzy", his office said, adding the politically and legally beleaguered 73-year-old was likely dehydrated but "in good condition".

"The prime minister arrived at the Sheba medical centre a short while ago," Netanyahu's office said in a statement of Israel's largest hospital, located near Tel Aviv.

"He is in good condition and undergoing medical evaluations," the statement said.

In a second statement, his office said Netanyahu on Friday spent time in the scorching heat of the Sea of Galilee, in Israel's north.

"Today, he felt slightly dizzy, and at the advice of his personal physician, Dr Zvi Berkowitz, was taken to Sheba's emergency department," the statement said.

"The initial examinations showed normal findings," it added. "The initial evaluation is dehydration."

The premier will undergo a series of further tests, his office said.

Netanyahu, who was reelected late last year, is heading a hard-right coalition whose proposed judicial overhaul has triggered weekly demonstrations since January.

The premier is also standing trial for corruption charges he denies.

In October, Netanyahu was hospitalised for overnight. His office said at the time he was feeling ill while observing the Jewish fast of Yom Kippur.