Israeli Prime Minister Benjamin Netanyahu on Thursday fought back against an agreement by his political opponents for a government of left-wing, centrist and right-wing parties aimed at unseating him.

Netanyahu, facing the prospect of an end to his 12-year run as premier, said on Twitter "all legislators elected by votes from the right must oppose this dangerous left-wing government", and he targeted historic Arab participation in the coalition.

The right-wing leader mounted the social media attack the day after centrist politician Yair Lapid's announcement, about 35 minutes before a Wednesday night deadline, that he had succeeded in forming a governing coalition.

Under the deal, nationalist Naftali Bennett, 49, a former defence minister and a high-tech millionaire, would become prime minister and hand over the post to Lapid, 57, a former TV host and finance minister, in about two years.

A parliamentary session, in which the government can be approved by a simple majority of legislators, could be some 10 days away, leaving slight room for Netanyahu, Israel's longest-serving leader, to twist arms.

The coalition agreement capped a March 23 election in which neither Netanyahu's Likud party and its allies nor their opponents won a majority in the legislature. It was Israel's fourth national ballot in two years.

The governing lineup comprises a patchwork of small and medium parties from across the political spectrum, including for the first time in Israel's history one that represents its 21% Arab minority - the United Arab List (UAL).

On Twitter, Netanyahu - who once drew accusations of racism by urging his supporters to get out and vote because "Arabs are flocking to the polls in droves" - highlighted the new alliance's links with UAL leader Mansour Abbas.

Netanyahu posted an old video clip of Bennett saying that Abbas "visited terrorist murderers in jail" after a 1992 attack in which Arab citizens of Israel killed three soldiers.

Spokesman for the United Arab List did not immediately respond to a request for comment.

Diverse Lineup

Members of the prospective government have little in common other than a desire to oust Netanyahu, who is also on trial on corruption charges. He denies any wrongdoing.

The roster includes Bennett's Yamina (Rightward), centre-left Blue and White, headed by Defence Minister Benny Gantz, the left-wing Meretz and Labour parties, former defence minister Avigdor Lieberman's nationalist Yisrael Beitenu party and New Hope, a right-wing party headed by former education minister Gideon Saar, who broke away from Likud.

Political analysts expect Netanyahu to try to pick off what one described as "low-hanging fruit", seizing upon Yamina members who are unhappy about joining forces with Arab and leftist lawmakers.

"The coalition's test...is to be sworn in - that won't be without rough patches and problems," she said on Army Radio on Thursday.

Netanyahu controls 30 seats in the 120-member Knesset, almost twice as many as Lapid's Yesh Atid party, and is allied with at least three other religious and nationalist parties.

During his tenure as prime minister, Netanyahu has been a polarising figure at home and abroad. His rivals have cited the criminal charges against him as a main reason why Israel needs a leadership change, arguing that he might use a new term to legislate immunity to shield himself.

A source involved in the coalition talks said the proposed new government would try to retain consensus by avoiding hot-button ideological issues such as whether to annex or cede occupied West Bank territory that Palestinians want for a state.

Bennett has said that the creation of an independent Palestine would be suicide for Israel. He made annexation of parts of territory that Israel captured in the 1967 Middle East war a major feature of his political platform, but following through on that with the broad new coalition looked to be politically unfeasible.

However, any flareup along the Israel-Gaza border, after 11 days of fighting that ended with a ceasefire nearly two weeks ago, could text the coalition's cohesion.

The new government, if it is sworn in, will face considerable challenges. As well as Iran and the moribund peace process with the Palestinians, it also faces a war crimes probe by the International Criminal Court and economic recovery following the coronavirus pandemic.