Israel will in “no circumstances” send troops into Hamas tunnels in and around Gaza, a retired general has said.

The sprawling tunnel network would be a “death trap” for the Israel Defense Forces (IDF) if soldiers enter them, said Yair Golan, a former IDF deputy chief of staff.

Hamas started building the labyrinthine underground system almost two decades ago, initially to bring goods into the besieged Gaza Strip and later for military purposes.

“The moment that we get to the tunnels, or regarding the tunnels we’ve already reached – they become a death trap for the enemy,” reserve Maj Gen Golan told Army Radio.

“The wisdom is to find the entrance and seal them, or send in smoke that will cause the enemy to come out and will harm them.”

Footage released by the IDF on Thursday morning showed troops engaged in street battles, with tanks firing in the midst of urban areas and soldiers holed up in a building responding to gunfire from across the road.

Israeli media reported that IDF troops were engaging an elite Hamas unit in an undisclosed location as they came under mortar and anti-tank shelling. No Israeli casualties were reported there.

In Israel’s highest-ranking casualty of the ground operation, Lt Col Salman Habka was reported killed in fighting in Gaza on Thursday.

He was involved in saving children in the Hamas attack on the south of Israel last month, according to reports.

Meanwhile, an IDF spokesman said on Thursday that the ground operation in Gaza was proceeding as planned.

“The troops continue to topple Hamas’s defence lines in the northern Gaza Strip and to take over central areas. We continue to intensify our actions and to progress according to the plan and the objectives that we set ourselves,” said Rear Admiral Daniel Hagari.

Social media posts from Gaza suggest that the IDF is continuing to advance deep into the Strip towards the Mediterranean Sea coast.

Open source data showed that, by Thursday, the troops could be a few kilometres away from cutting the north of Gaza from the rest of it.

Israeli forces were also seen making advances along the Gaza border, feeding into previous speculation that Israel might be seeking to establish a buffer zone there.