A group of Israeli diplomats wants to sue Iran's President Mahmoud Ahmadinejad for incitement to genocide.
Mr Ahmadinejad has made a series of strong anti-Israel comments
Lawyers are preparing to send a file on Mr Ahmadinejad, who has repeatedly called for the destruction of Israel, to the International Court of Justice.
Among those backing the move are former Israeli ambassadors to the UN and the US and a former cabinet minister.
They say Mr Ahmadinejad's comments have broken a 1948 UN genocide convention, to which Iran is a signatory.
Israeli legal experts have examined a series of comments made by Mr Ahmadinejad to assess whether his remarks defy the convention.
Mr Ahmadinejad has made a series of anti-Israeli remarks since winning Iran's presidential election in 2005.
According to reports in Israeli media, the diplomats engaged the Jerusalem Centre for Public Affairs, headed by former UN ambassador and government adviser Dore Gold, to establish whether a prosecution would be justified.
An advisory document recommending moving ahead with a prosecution is almost complete, Israeli news website Ynetnews.com reported.
The document lists a series of comments by Mr Ahmadinejad including a remark, made in October 2005, expressing a wish to "wipe Israel off the map", Ynetnews.com said.
In April 2006 he described Israel as "a rotten and dried-up tree which will be destroyed by one storm".
The legal document is expected to conclude that Mr Ahmadinejad's comments constitute "direct and public incitement to commit genocide".
"From our preliminary assessment, there is no question that Ahmadinejad violated the genocide convention, which specifically addresses the issue of incitement to genocide," Mr Gold told the Associated Press news agency.
The UN convention defines genocide as the intent or actual destruction, in whole or in part, of a national, ethnical, racial or religious group.
It describes any "direct and public incitement to commit genocide" as a breach of the convention.
The International Court of Justice (ICJ) is the court of the UN, based in The Hague.
It makes rulings in disputes, although many countries often dispute its jurisdiction. The court also gives non-binding advisory opinions when asked to do so by relevant UN organisations.
In 2004 the court ruled that parts of the barrier Israel is building around the West Bank ran through Palestinian land and were illegal.