Benjamin Netanyahu has urged the world to reject a Palestinian unity government, saying Hamas is a "terrorist" group bent on the destruction of his country.
The Israeli prime minister said on Sunday that an impending Hamas-Fatah deal to mend ties would strengthen "terrorism" in the Middle East, not bolster peace.
"I call on all responsible elements in the international community not to rush to recognise a Palestinian government which has Hamas as part of it and which is dependent on Hamas," he said.
"Hamas is a terrorist organisation that calls for the destruction of Israel and the international community must not embrace it. That would not bolster peace, it would strengthen terror."
Hamas has controlled the occupied Gaza Strip since 2007 when it kicked out Fatah after winning an election. Fatah controls areas of the West Bank.
The factions agreed in April to form a unity government, a move that led to Israel freezing US-brokered talks with Palestinian leaders.
Mahmoud Abbas, the Palestinian president, said on Saturday that he would formally present the new government on Monday.
"Israel wants to punish us for agreeing with Hamas on this government," he said, adding that the Netanyahu administration would "boycott the government the moment it is announced".
Palestinian officials reported last-minute haggling on Sunday. Khalil al-Haya, a top Hamas official in Gaza, said there could be a delay due to a disagreement over the Palestinian ministry for prisoners held by Israel.
On Saturday, a Palestinian official said Israel had denied requests by three Gaza-based Palestinians expected to be named as ministers to attend the new government's swearing-in ceremony in the West Bank. Israel pulled its troops out of Gaza in 2005 in a "disengagement", but still controls the borders, sea and airspace.
The US and the EU, which are the largest donors to Palestinian agencies, have signalled that they are willing to give the new unity government a chance. The US, which considers Hama a "terrorist" group, has said it will not make any decision on support until it has seen who is in the government.
Abbas has promised the cabinet will accept international calls to renounce violence and recognise Israel's right to exist.