Israel's prime minister said on Tuesday he is "deeply troubled" by the United States' decision to maintain relations with the new Palestinian unity government, urging Washington to tell the Palestinian president that his alliance with the Hamas militant group is unacceptable.

The blunt language used by Prime Minister Benjamin Netanyahu reflected the Israeli government's disappointment and frustration over the international community's embrace of Palestinian President Mahmoud Abbas' new unity government.

Netanyahu has urged the world to shun the government because it is backed by Hamas, an Islamic group that has killed hundreds of Israelis in attacks over the past two decades. But late on Tuesday, both the US and European Union said they would give Abbas a chance.

"I'm deeply troubled by the announcement that the United States will work with the Palestinian government backed by Hamas," Netanyahu told The Associated Press, saying the group has murdered "countless innocent civilians".

"All those who genuinely seek peace must reject President Abbas' embrace of Hamas, and most especially I think the US must make it absolutely clear to the Palestinian president that his pact with Hamas, a terrorist organization that seeks Israel's liquidation, is simply unacceptable," he said.

US-led peace talks collapsed in late April after the Palestinians announced a surprise unity deal between leaders in the West Bank and the Hamas-run Gaza Strip, with Israel saying it would not negotiate with any government backed by the Islamists.

Under the terms of the agreement, Hamas and Fatah, which dominates the West Bank administration, worked together to formulate an interim government of politically independent figures that will prepare for elections within the next six months.

The government was sworn in on Monday in front of Abbas, with Washington publicly offering its backing several hours later.

"At this point, it appears that President Abbas has formed an interim technocratic government that does not include ministers affiliated with Hamas," State Department spokeswoman Jen Psaki told reporters.

"With what we know now, we will work with this government," she added. To add to the embarrassment, Netanyahu told the security cabinet on Sunday that US Secretary of State John Kerry had promised Israel that Washington would not immediately recognize the new government, the Haaretz newspaper reported, quoting two ministers present at the meeting.

"I have to say I do not understand this American announcement," said Intelligence Minister Yuval Steinitz, accusing Washington of saying one thing behind closed doors and another in public.

"You cannot present it as a Hamas government internally, then present it publicly as a government of technocrats," he told army radio.

AFP-AP