Israel worries Iran will secure a windfall in sanctions relief in renewed nuclear negotiations with world powers but will not sufficiently roll back projects with bomb-making potential, Israeli Prime Minister Naftali Bennett said on Sunday.

"Israel is very worried about the readiness to remove the sanctions and to allow a flow of billions (of dollars) to Iran in exchange for unsatisfactory restrictions in the nuclear realm," Bennett told his cabinet in televised remarks, Reuters reported.

"This is the message that we are relaying in every manner, whether to the Americans or to the other countries negotiating with Iran."

Negotiators will convene in Vienna on Monday in a last-ditch effort to salvage a nuclear deal which the US under then-President Donald Trump quit in 2018, reimposing sanctions on Iran. That led to breaches of the deal by Tehran, and dismayed the other powers involved.

Six rounds of indirect talks were held between April and June. The new round begins after a hiatus caused by the election of a new Iranian president, Ebrahim Raisi, a hardline cleric.