US Secretary of State Antony Blinken said on Friday Washington wanted to see "results" showing more aid was reaching Gazans after Israel announced it would open routes into the territory.

Israel announced on Friday that it would allow "temporary" aid deliveries into famine-threatened northern Gaza, hours after the United States warned of a sharp shift in its policy over Israel's war against Hamas militants.

"We welcome the steps that have been initiated by Israel," Blinken said at a meeting with EU officials in Belgium. 

"These are positive developments but the real test is results and that's what we're looking to see in the coming days and in the coming weeks."

Blinken said the United States was watching to see if aid begins "effectively reaching people who need it throughout Gaza" and if humanitarian workers can deliver it in safety. 

The top US diplomat said Washington would check on the number of aid trucks entering if they could circulate, and if indicators showing the population is on the brink of famine improve.

He said it was "critical that we see an independent, thorough and fully publicized investigation" into the killing of aid workers from World Central Kitchen.

"We're looking to see a public accounting and we're looking to see accountability in its wake," he said.

More broadly, he added that Israel needed to "make it a priority" to minimize civilian casualties in Gaza. 

"That too, is a critical test," he said. 

The bloodiest-ever war in Gaza follows a Hamas attack on 7 October that resulted in the deaths of 1,170 people in Israel, most of them civilians, according to an AFP tally based on official Israeli figures.

Palestinian militants also took around 250 hostages, about 130 of whom remain in Gaza, including 34 whom the army says are dead.

Israel's retaliatory military assault has killed at least 33,037 people, according to the health ministry in Hamas-run Gaza.

The United Nations has warned of "catastrophic" hunger in the besieged Palestinian territory.