Tzipi Livni has become Israel’s opposition leader in the Knesset as part of a deal agreed with Avi Gabbay’s Labour Party.

Ms Livni has agreed that her Hatnuah Party will again run in the next parliamentary elections in the Zionist Union electoral alliance with Labour.

But Israeli media said the terms of the alliance had not been unannounced and it remains unclear which party leader would be the bloc’s candidate for prime minister.

The next election must be held before November 2019.

Monday’s deal sees Ms Livni return to the position she held between 2009 and 2012, when she was leader of the Kadima Party.

Mr Gabbay cannot hold the position because he is not an MK.

“We are making a significant step today in building an alternative to the incumbent government, a camp that can constitute a new  hope for the people of Israel,” the Labour leader said in a statement.

Ms Livni brings “a wealth of experience, especially on security and diplomatic matters,” he added.

He later tweeted a selfie of himself with Ms Livni carrying the message: “We said yes!”

אמרנו כן! @Tzipi_Livni pic.twitter.com/NH5aOl03Rp

— Avi Gabbay אבי גבאי (@GabbayAvi) July 23, 2018

Ms Livni replaces Isaac Herzog, who stepped down earlier this month to take up his new role as chairman of the Jewish Agency.

The Zionist Union took 18.7 per cent of the vote in the last election in 2015, winning 24 seats in the 120-seat chamber.

But the alliance trailed Benjamin Netanyahu's Likud, which took 30 seats.