Election in Israel: PM Benjamin Netanyahu at his Likud party headquarters in Tel Aviv. (Reuters)

Israel's election remained too close to call Wednesday morning, with television stations carrying unofficial results showing Prime Minister Benjamin Netanyahu tied with his main rival, former military chief Benny Gantz.

An official tally was still hours, perhaps days off, but the outcome appeared to be taking shape along the expected lines -- the Netanyahu-led right-wing block more or less even with Gantz's center-left.

With no single-party majority in the Knesset's 120 seats, there will likely be weeks of coalition talks before a new government is formed.

The ballot's wildcard, former Defence Minister Avigdor Lieberman, emerged as a likely kingmaker as head of the far-right Yisrael Beitenu party.

Lieberman has been pushing for a unity government comprised of the biggest parties. He declined to back Netanyahu's bid to form a narrow right-wing and religious coalition after an April election, bringing about Tuesday's unprecedented repeat vote.

Addressing Likud party faithful, Netanyahu, the longest-serving Israeli premier ever, sipped water frequently and spoke in a hoarse voice. He made no claim of victory or concession of defeat, saying he was awaiting a vote tally. His appearance in the dead of night was a far cry from his triumphant - and in the end premature - declaration five months ago that he had won a close election.

Gantz was more upbeat, telling a rally of his Blue and White party that it appeared "we fulfilled our mission", and he pledged to work towards forming of a unity government.

Israel's main TV stations, Channel 12 and 13, carried unofficial results showing Netanyahu's Likud and Gantz's Blue and White parties tied with 32 seats each. With support from smaller religious and liberal rivals, each was projected to command of bloc of about 55 or 56, just short of a majority.

Which leaves Lieberman, whose party was forecast to win 9 seats. Lieberman on Wednesday reiterated his call for a unity government, but said he had not yet spoken to Gantz or Netanyahu.

"There is only one option - a national unity government, a broad, liberal government, and we will not join any other," he told reporters.

Only 35% of votes had been officially counted by Wednesday morning, showing a tight race between Likud and Blue and White.

Netanyahu, who highlighted his close relationship with U.S. President Donald Trump during the campaign, said in his 3 a.m. speech at Likud election headquarters in Tel Aviv that he intended to establish a "strong Zionist government" that would reflect the views of "many of the nation's people".

Gantz has ruled out joining an administration with Netanyahu if the Israeli leader is indicted on looming corruption charges.

The Joint Arab List made a strong showing in Tuesday's election and was projected to capture 12 seats in parliament, compared with 10 won by various Arab factions in April's election.

Three corruption investigations and the Israeli attorney general's announced intention to charge him with fraud and bribery have also chipped away at Netanyahu's seeming invincibility, 10 years into consecutive terms as prime minister marked by a sharp focus on security that resonated with voters.

Netanyahu, 69, who can argue at a pre-trial hearing in October against indictment, has denied any wrongdoing.

An election loss could leave him more at risk of prosecution in the graft cases, without the shield of parliamentary immunity that his current political allies had promised to seek for him.

Campaigns run by Likud and Blue and White pointed to only narrow differences on many important issues: the regional struggle against Iran, the Palestinian conflict, relations with the United States and the economy.

An end to the Netanyahu era would be unlikely to bring about a significant change in policy on hotly disputed issues in the peace process with the Palestinians that collapsed five years ago.