The Israeli military said on Wednesday night that it had taken “tactical control” over the Philadelphi Corridor — a sensitive strip of Gaza along its border with Egypt — in a move that could further tax Israel’s already strained ties with Cairo.

Rear Adm. Daniel Hagari, the Israeli military spokesman, said the zone was “Hamas’s oxygen tube” and had been used by the Palestinian armed group for “smuggling munitions into Gazan territory on a regular basis.” He said that Hamas had also built tunnels near the Egyptian border, calculating that Israel would not dare strike so close to Egyptian territory.

Israeli officials have said seizing the narrow, roughly nine-mile-long area holds crucial importance for preventing Hamas from rearming itself through cross-border smuggling. “It must be in our hands; it must be closed,” Prime Minister Benjamin Netanyahu of Israel told reporters in December, after being asked whether Israel still intended to capture the zone.

An Israeli military official, who briefed reporters Wednesday on condition of anonymity to comply with military protocol, said that troops had identified at least 20 tunnels running from Gaza into Egypt, some of them only recently discovered.

But in briefing reporters later on Wednesday night, Admiral Hagari stopped short of claiming that the tunnels crossed the border.

“I can’t say now that all of these tunnels cross into Egypt,” he said. “We’ll inspect that, pass along the intelligence” to Egypt. The tunnel shafts in Gaza “are located in proximity to the border with Egypt, including in buildings and homes,” he added. “We’ll investigate and take care of each of those shafts.”

After the Israeli announcement, Egypt’s state-run Al-Qahera News channel quoted an unnamed senior official saying “there is no truth” to claims of tunnels under the border.

“These lies reflect the magnitude of the crisis facing the Israeli government,” the official said, adding, “Israel continues its attempts to export lies about on-the-ground conditions for its forces in Rafah in order to obscure its military failure and to find an escape for its political crisis.”