NATO continued its intensified assault on Libya’s capital on Thursday, sending missiles into Moammar Gaddafi’s compound hours after the longtime leader appeared on state television to dispel rumors that he had died. The attacks continued a major escalation that NATO says will help protect civilians, but Libyan government officials say they are simply attempts on their leader’s life.

The attacks came on the same day that Defense Secretary Robert M. Gates said that Western allies needed to take a cautious approach to dealing with Libya’s rebels.

NATO attacks on Tripoli have spiked this week since a spokesman said allies had entered the second phase of the campaign. Attacks on bunkers and other sites in the city that NATO defines as key targets, including tanks, missile launchers and ammunition depots as well as command-and-control sites, rose from three on Monday to 11 on Tuesday and 10 on Wednesday.

Gaddafi appeared on Libyan television late Wednesday. Hours later, missiles blasted several areas in his sprawling Bab al-Aziziya compound in Tripoli, located just over a mile from the hotel in which his videotaped appearance was recorded.

NATO Secretary General Anders Fogh Rasmussen denied any connection between Gaddafi’s appearance and the attack on the Tripoli compound, saying that “we do not target individuals, we target military capabilities that can be used to attack civilians,” although he has in the past called for Gaddafi to step down.

Any facility used for command-and-control operations is a “legitimate target,” Rasmussen said in an interview during a visit to Washington on Thursday, describing himself as “pleased to see opposition forces gain ground in recent days.”

Using NATO strikes to enable opposition gains, Rasmussen said, did not constitute taking sides in the nearly three-month-long conflict. “In the sense that Gaddafi attacks” civilians, he said, “opposition progress will protect civilians.”

But when the NATO operation might end remained unclear. NATO’s original 90-day planning for the operation will end next month and members will have to determine ongoing contributions, Rasmussen said.

Although the Obama administration has praised opposition leaders — a senior member of the opposition political council, Mahmoud Jibril, is due at the White House on Friday for a meeting with national security adviser Thomas E. Donilon — senior U.S. officials continue to express concern about the makeup of the rebel fighting force.

“With the exception of some of the people at the top of the opposition or the rebels in Libya, we don’t know who they are,” Gates said at a town hall meeting at Camp Lejeune, N.C., on Thursday. “We deal with a handful of people in Benghazi, but we forget about those who led the uprisings in cities all over Libya when this whole thing started. And who are they?

“We have seen reports that there are some extremists that are fighting for the opposition,” Gates said. “I think we have to keep a wary eye on it.”

Deputy Secretary of State James B. Steinberg told senators Thursday that international sanctions against the Libyan government were beginning to bite, pointing to fuel shortages, dwindling cash supplies and blocks on the export of oil.

“Their access to the financial system has been badly damaged. And so we do see signs that this is creating real pressure there,” he told the Senate Foreign Relations Committee.

The British government offered on Thursday, during a visit from the chairman of the rebel Transitional National Council, Mustafa Abdel Jalil, to supply uniforms and bulletproof vests to police in opposition-held areas.

The British government also invited the rebels’ transitional council to open an office in London.

The NATO strikes Thursday hit a bunker complex “that was used to coordinate attacks against civilian populations,” the alliance said in a statement, although a Libyan government spokesman, Moussa Ibrahim, said the facility that was hit — which was inside the walls of Gaddafi’s expansive residential and governmental compound — was a sewage treatment plant. Gaddafi was not in the compound at the time, he said.

Reporters visiting the complex on an official government tour of the damage were able to peer into a reinforced-concrete chamber that had partially caved in. At least 30 feet deep, it smelled of fuel, not sewage, and a ventilation shaft and several satellite dishes appeared to indicate a specialized purpose for the site.

Elsewhere in the complex, a separate missile dug a crater into what appeared to be rebar and concrete underneath a paved road.

The strikes were close to the ruins of the building hit by U.S. airstrikes in 1986 and preserved by Gaddafi as a monument.

Ibrahim said three people had died in the attack on Bab al-Aziziya and 27 were injured. Civilians have streamed into Gaddafi’s compound every evening since the NATO campaign started in mid-March, serving as human shields. Some civilians could be seen in the complex — which NATO also bombed March 20 and April 30 — while it was being shown to foreign reporters Thursday.

“It’s an official administrative facility that doesn’t have any military applications,” Ibrahim said of the complex. “These people are civilians.”

DeYoung reported from Washington. Staff writers Mary Beth Sheridan in Washington and Joby Warrick in Nuuk, Greenland, and special correspondents Karla Adam in London and Portia Walker in Benghazi contributed to this report.