"Over the past 24 hours, IDF soldiers have begun a targeted ground operation in the central and southern Gaza Strip in order to expand the security zone between the northern and southern parts," army spokesman Avichay Adraee said on X.

Movement along Salaheddin Road between the north and south of the Gaza Strip is prohibited "for your safety", he said.

"Instead, travel from northern Gaza to the south is possible via the Al-Rashid coastal road," Adraee added, without spelling out whether that meant movement from south to north was banned.

Asked by AFP for clarification, the army had no immediate comment.

An official from Gaza's Hamas-run interior ministry said the Israeli army had closed what it calls Netzarim Junction, on Salaheddin Road just south of Gaza City, on Wednesday evening.

The official said that Israeli tanks had deployed at the junction, where the road artery crosses Israel's main supply route, "following the withdrawal of American special security forces yesterday (Wednesday) morning".

He was referring to American private security contractors deployed in February after the pullback of Israeli forces under the terms of a January 19 ceasefire.

The first stage of the ceasefire expired early this month amid deadlock over next steps.

Israel rejected negotiations for a promised second stage, calling instead for the return of all of its remaining hostages under an extended first stage.

That would have meant delaying talks on a lasting ceasefire, and was rejected by Hamas as an attempt to renegotiate the original deal.

After weeks of stalemate, Israel resumed its air campaign in Gaza early Tuesday with a wave of deadly strikes that drew widespread international condemnation. On Wednesday, it announced it was resuming ground operations too.