Israel's chief peace negotiator Tzipi Livni is appealling against a bill approved by ministers which aims to curb peace talks on the future of Jerusalem.
The draft law, a copy of which was seen by AFP, seeks to prevent any negotiations on the future of the Holy City without first obtaining a two-thirds majority of 80 of the 120 members of the Israeli parliament.
It was approved late on Sunday by a 5-4 majority within the nine-member ministerial committee responsible for preparing draft legislation to put to parliament.
"Since there have been occasions in the past when talks have begun on handing over parts of the city, we must legislate to ensure that this possibility does not arise" without a two-thirds majority, which "cannot be achieved easily", the text reads.
Livni, who serves as justice minister and heads the centrist HaTnuah, voted against the bill along with three other ministers, one from her party and two from the centrist Yesh Atid.
Were the bill to be passed, it would mean negotiators could not even begin discussing Jerusalem without first obtaining a mandate from two-thirds of MPs.
"She is going to file an appeal today," her spokeswoman Maya Bengel told AFP, without giving further details.
Prime Minister Binyamin Netanyahu reportedly opposes the bill.
Livni's appeal means the bill will now be put to the full 22-member cabinet, in a move that will significantly reduce its chances of going forward as the final decision on whether to put it to a vote will be in Netanyahu's hands, the Maariv newspaper reported.
The two sides resumed direct talks for the first time in nearly three years in Washington at the end of July, following intense US pressure.
The future status of Jerusalem is one of the most sensitive issues of the Israeli-Palestinian conflict.
Israel captured East Jerusalem during the 1967 Six Day War and later annexed it in a move never recognised by the international community.
Israel regards the whole city as its "eternal, indivisible" capital, but the Palestinians want the currently-occupied eastern sector as capital of their future state.