"Keep an eye on them, so they won't come up with any tricks," Mr Mordechai said on his last day in the job. He was unceremoniously fired by Mr Netanyahu two days ago. He angered the Prime Minister by proposing to head a new centrist party in the elections on 17 May.
His unprecedented attack, which was the first time an outgoing defence minister has warned the intelligence community against the folly of a prime minister, follows two days of verbal sparring by the former political allies that began with Mr Mordechai's dismissal.
It came hours before the former military man, a relative moderate in Mr Netanyahu's government, announced his candidacy for prime minister on a new centrist ticket.
Two other defectors from Mr Netanyahu's Likud party, the former finance minister Dan Meridor and the ex-mayor of Tel Aviv Roni Milo, as well as the former army chief-of-staff Amnon Lipkin-Shahak, have joined him to form a new party.
On Monday, Mr Netanyahu won re-election as head of Likud. But Mr Mordechai's bid for the Israeli leadership is a serious blow to Mr Netanyahu's chances for re-election on 17 May.
Of all the politicians who have split from Likud, Mr Mordechai is considered the most formidable challenger to Mr Netanyahu, whose coalition disintegrated last month, forcing him to call for new elections for both parliament and for prime minister.
Mr Mordechai, whose family hails from Iraqi Kurdistan, appeals to many Likud voters, who tend to emphasise the issue of security. Many are Jews of Middle Eastern origin.
An opinion poll published in the daily newspaper Yedioth Aharonot found that 32 per cent of those who voted for Mr Netanyahu in the 1996 elections would consider voting for the new party headed by Mr Mordechai.
Some analysts said the new party may represent the beginnings of a political earthquake in Israel, where politics have been dominated by the two biggest parties, Likud and Labour, since the 1970s.
Such a shake-up was made possible in part by the latest peace deal signed between a Likud-led Israeli government and the Palestinians. By signing on to a peace process it despised, Likud narrowed the gap between its ideology and that of the Labour party, opening the way for a centrist party to emerge.
Such a centrist party is likely to be more conciliatory in peace talks with Palestinians than the Netanyahu government. Mr Mordechai is considered a moderate in the peacemaking process and Lipkin-Shahak headed the negotiations that led to the second Israeli- Palestinian peace agreement, known as Oslo II.
Mr Netanyahu has already tried to brand the centrist party as "leftist", a code word that to Israelis signals capitulation to Palestinian demands. On Sunday, he accused Mr Mordechai of organising "a conspiracy to topple the government" and said that was what led him to dismiss the defence minister.
Mr Mordechai has launched his own attacks in return, suggesting Mr Netanyahu had been planning a colourful operation in Lebanon as a pre-election ploy to increase his popularity.
On Sunday, Mr Mordechai used the Bible against Mr Netanyahu, quoting Psalm 120 and hinting that he didn't believe the Prime Minister was serious about pursuing peace: "Too long have I lived among those who hate peace," Mr Mordechai said.Reuse content