President Donald Trump's administration informally gave a required notification to Congress on the sale, which could "significantly change the military balance in the Gulf and affect Israel's military edge," said Representative Eliot Engel, a Democrat who leads the House Foreign Affairs Committee.

The United Arab Emirates -- which has been increasingly assertive in the region, including in Yemen and Libya -- sought the advanced warplanes as it spoke to the United States ahead of its landmark recognition of Israel last month.

The normalization -- followed by similar moves by Bahrain and Sudan -- was a diplomatic coup for Prime Minister Benjamin Netanyahu, but the Jewish state has also long opposed US sales of top-end warplanes to any Arab states including Egypt and Jordan, which already have peace treaties with Israel.

But Netanyahu indicated last week that Israel would not object to the UAE deal after Defense Minister Benny Gantz, his uneasy coalition partner, received assurances during a trip to the Pentagon that Israel would maintain its military edge.

US Defense Secretary Mark Esper was visiting Israel on Thursday for talks with Gantz about bolstering the US ally's military capacities.

A State Department official declined to confirm the UAE deal, saying that it does not comment on notifications to Congress.

The notification comes five days before US elections in which Trump is trailing in published polls to Democrat Joe Biden.

Congress, where the Democrats control the House of Representatives and are seen as having a chance of winning the Senate, has the power to block the UAE sale.

"The export of this aircraft requires very careful consideration and Congress must analyze all the ramifications. Rushing these sales is not in anyone's interest," Engel said.