BEIRUT — The Israeli military kept up its heavy bombardment of a once densely populated area adjoining Beirut on Friday after saying its ground troops were battling new targets in southern Lebanon, signaling a widening of the fighting that could further undercut cease-fire efforts.

The airstrikes on the Dahiya area, south of Beirut, where the militant group Hezbollah holds sway, were the latest in a string of bombings this week. The Israeli military issued new evacuation warnings just after dawn Friday, and missiles began landing soon afterward, leveling at least one high-rise residential building that had been identified in the warnings and sending a thick dust cloud through the surrounding streets.

There were no immediate reports of casualties. Most residents fled the Dahiya weeks ago when Israel’s bombing campaign began.

There were also signs that Israel’s ground invasion was broadening and that its troops were battling Hezbollah fighters deeper inside Lebanese territory.

The Israeli military said Thursday that its commandos were conducting ground operations against “several new enemy targets” in Lebanon.

A senior Lebanese security official, speaking on condition of anonymity, said Israeli ground forces were operating around the town of Chamaa.

Hezbollah also said overnight that it had attacked Israeli soldiers near Tayr Harfa, a town south of Chamaa that it described as part of its “secondary line” of defense and where clashes had not been previously reported. On Friday, the group said it had fired rockets at Israeli troops on the outskirts of Talloussah, another town.

A widening Israeli offensive would undermine U.S. diplomatic efforts to stem the conflict between Israel and Hezbollah, which is backed by Iran. The Biden administration has renewed a push to contain the fighting after rounds of shuttle diplomacy over the past year failed.

Although Israel’s military leaders originally hoped to conduct a limited ground operation that focused solely on the first line of Lebanese villages along Israel’s northern border, they decided to slightly expand that range, Amir Avivi, a retired Israeli brigadier general, said in an interview.

The reason, he said, was that Israeli military officials realized that they needed to do more to clear out Hezbollah’s military installations and believed that a broader offensive could force the armed group into making a diplomatic settlement on terms more favorable to Israel.

“There’s an understanding that we need to ramp up the pressure and clear out a greater area, and that’s what they’re doing,” Avivi said.

But there has been no public indication that Hezbollah or its patron, Iran, are willing to acquiesce to Israel’s demands, which include the group’s withdrawal from areas near the Israel-Lebanon border.