Rabbi Israel Hager votes for Israel's parliamentary election at a polling station in Bnei Brak, Israel, Tuesday, April 9, 2019. (AP Photo/Oded Balilty)

Tel Aviv - Israelis headed to polling stations on Tuesday to vote in the country's general election, in what is being seen as the toughest challenge in years for current Prime Minister Benjamin Netanyahu.

The emergence of popular former army chief Benny Gantz on the political scene, coupled with a string of corruption scandals resulted in a difficult election campaign for Netanyahu.

"With God's help the state of Israel will win," Netanyahu said as he cast his vote together with his wife Sara in Jerusalem in the morning.

"There are many people who want us to continue this fantastic journey which brought Israel to its best decade in history, and we have so much more to do," Netanyahu said afterwards, as he urged Israelis to vote for his right-wing Likud party.

His main rival Gantz, leader of the new centrist Blue and White party, cast his vote in his hometown Rosh Haayin and said: "This is a day of hope. A day of unity. I am looking the people of Israel in the eyes and telling them - this change is possible."

"I offer myself as Israel's prime minister and together, we will take this new path. I call out to all of you - let's respect democracy and go vote," Gantz added.

Both leaders continued their vigorous campaigns throughout the day as their parties battled to garner the largest number of seats in the next parliament.

Netanyahu warned that he would lose if right-wing voters didn't come out in force for Likud. Gantz stated that anything other than a Blue and White vote amounted to a vote for Likud.

From Ramallah, Palestinian President Mahmoud Abbas said he hoped Israeli voters would "follow the right path to reach peace."

"They (Israel) should understand that peace is in our interest as well [as] theirs and [those of the] whole world," Abbas said in a statement published by Palestinian news agency WAFA.

For the past decade that Netanyahu has served as prime minister, the peace process has remained stalled. Days before the election, in an apparent bid to win over right-wing voters, he vowed to annex Jewish settlements in the West Bank.

Gantz has spoken in favour of a peace agreement while maintaining Jerusalem as Israel's capital and retaining the settlement blocs.

The tight race between Likud and the Blue and White party materialized after Gantz teamed up with lawmaker Yair Lapid to form the new centrist party, which has had a slight edge in most polls over Netanyahu's Likud.

However, polls have shown that most Israelis believe Netanyahu will be the one to form the next coalition.

This is partly because the right-wing bloc of parties is expected to be larger in the Knesset than the centre-left bloc, which could hand Netanyahu the mandate to retain the premiership.

Of a handful of voters who spoke to dpa at a polling station in the liberal city of Tel Aviv, the majority said they were voting Blue and White. "Only Blue and White!" one woman shouted on her way to vote.

Adi Grinberg said she was hoping for a revolution and, referring to Netanyahu by his nickname, said: "Bibi has to go."

"If I know something isn't good then we need to see something different. Maybe the something else will be worse - I don't know - but we have to at least give a chance for change, improvement and a better life," Grinberg told dpa.

"I just want to try to bring Bibi down," said Danielle, who declined to give her surname, but neither Danielle nor Grinberg had high expectations of that happening.

"I think Bibi will win again and the country ... will only continue to deteriorate," Grinberg predicted.

Yaarit, who withheld her surname, said she was resigned to a Netanyahu victory and had thus opted for Kulanu, a smaller centre-right party. The party focuses on socio-economic issues with a platform which seeks to reduce the cost of living and reduce social gaps.

"Nothing will change," Yaarit said.

Some 6.3 million people are eligible to vote, with a choice of some 40 parties.

Voter turnout by 6pm (1500 GMT) was 52%. The polls were set to close at 10 PM.