James Reynolds BBC Jerusalem correspondent

Israeli police officers are to interview officials from the ruling Likud party in an investigation into allegations of bribery during last week's internal party elections.

The polls were held to decide the party's list of parliamentary candidates for the general election scheduled to take place at the end of January.

Up until now, the general election campaign has been dominated by two issues - security and the economy - and by one party - Likud.

But now the allegations of bribery within the party have thrown up a third key issue: corruption.

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It has caused Israel's opposition parties to liven up.

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Already a number of them have come up with campaign slogans attacking Likud for dishonesty.

During last week's internal Likud elections, the party's central committee of about 3,000 members surprised many with its list of parliamentary candidates.

A number of relatively unknown candidates did well and some more established figures did badly.

Now a number of people involved in the election have come forward.

They allege that several candidates, or their supporters, bribed committee members to vote for them by offering money or benefits or, in one case, sexual favours.

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The allegations are being taken seriously.

The National Fraud Squad has begun an investigation and during the next week police officers are expected to interview a number of senior officials from the party.

The allegations have damaged Likud but the party is still expected to come out as the winner of January's general election.

Supporters of hawkish Foreign Minister Binyamin Netanyahu gained ground in the Likud party ballot.

Mr Netanyahu lost his bid to replace Ariel Sharon as Likud leader in an election last month.