Jerusalem  - With polls indicating that 20 per cent of voters are still undecided ahead of Tuesday's general elections, caretaker Prime Minister Ehud Olmert called Sunday on Israelis to vote in order to "to realize their democratic right and obligation."

Addressing ministers at the last cabinet meeting before the elections, Olmert said that "it is important that there be a high turnout so that the government that will be elected knows it has the full legitimacy, from a decisive majority of the residents of the state, to decide on the most important issues affecting our future."

"Voting in general elections is the essence of democracy. Here everything starts with voting," he said, according to a government communique.

"There is no other way in a democratic regime to influence the character and image of the government that will shape the fate of the country in the coming years," he said.

Polls published in Israeli dailies Friday - the last surveys before the election - showed the hawkish opposition Likud Party, headed by Benjamin Netanyahu, was heading for a narrow election victory over Olmert's Kadima party, which is led by Foreign Minister Tzipi Livni, as Olmert is not running for re-election.

According to the four separate polls published in Yediot Ahronot, Ma'ariv, Ha'aretz and the Jerusalem Post, the Likud can count on 25 to 27 seats in the 120-member Knesset, against 23 to 25 seats for Kadima.

The Likud had held a lead of five seats over Kadima for the past few weeks, but the centrist party has narrowed the gap to around two or three seats.

However, the bloc of right-wing parties - a minority in the outgoing parliament - is expected to obtain a clear majority with around 65 to 67 seats, against 53 to 55 for the left-to-centre bloc headed by Kadima.

That means that even if Livni manages to close the gap with Netanyahu and scores a shock victory, she could expect serious difficulties in forming a coalition.

Polls open at 7 am (0500 GMT) Tuesday at 9,263 polling stations across Israel, and close at 10 pm (2000 GMT), after which Israel's three television networks will release the results of exit polls.

First official results are not expected until Wednesday at the earliest. dpa