A senior Israeli official on Saturday admitted "mistakes" in intelligence assessments ahead of a brutal Hamas attack last weekend that took the country by surprise.

Palestinian militants early October 7 launched a multi-pronged assault, breaching the Gaza border barrier and targeting southern Israeli communities and army bases.

"It's my mistake, and it reflects the mistakes of all those making (intelligence) assessments," National Security Adviser Tzachi Hanegbi told a press briefing when asked about his recent remarks predicting no Hamas aggression.

"We really believed that Hamas learned the lesson from" its last major war with Israel in 2021, Hanegbi said.

More than 1,300 civilians and security forces have been killed since the attack began, according to Israeli officials, and at least 120 have been seized by militants and believed to be held captive in Gaza.

Hanegbi rejected negotiations towards any prisoner swap deal with Hamas.

"There's no way to negotiate with an enemy we have sworn to obliterate," he said.

Relentless Israeli air strikes on the blockaded Palestinian enclave over the past week have killed upwards of 2,200 including at least 600 children, Hamas officials said.