Efforts by the Kosovo Liberation Army to infiltrate Kosovo from Albania, apparently with the support of NATO airstrikes, represent a "new phase in the war," a top Yugoslav military commander said today.

Maj. Gen. Vladimir Lazarevic, who leads the key Pristina Corps in Kosovo, said a KLA offensive into Kosovo near the Morina border crossing in northern Albania this week was the vanguard of an eventual NATO invasion. He said his troops turned back the assault by 600 KLA "terrorists."

Sporadic fighting continued in the area today, he added, and this afternoon NATO launched heavy airstrikes west of the Kosovo town of Prizren, dropping 30 bombs in 30 minutes in support of the ethnic Albanian rebels, who are seeking to win Kosovo's independence from Serbia, Yugoslavia's dominant republic.

"This is the beginning of a new phase of aggression, the so-called land operation," Lazarevic said in a rare interview with a Western reporter.

Military analysts and observers on the Albanian side of the border said Thursday that the rebel action, which began Wednesday, was aimed at opening a new supply corridor for their forces in Kosovo. But they characterized the operation as "amateurism" because it came in a border region heavily defended by Yugoslav troops.

NATO and Pentagon officials have embarked on a public rehabilitation campaign for the KLA, which they once dismissed as a ragtag band of ill-disciplined gunmen. The rebels are now being described by U.S. and NATO officials as better trained and better led than before. One Pentagon official said at a briefing in Washington Thursday that at least 15,000 KLA fighters had made their way into Kosovo from Albania in recent weeks.

Lazarevic called the assertion nonsense. He said his troops, which are deployed throughout Kosovo, are engaged in "sporadic" fighting in pursuit of small, isolated rebel forces. He acknowledged that such actions could "continue for years." But he added flatly, "organized terrorist-separatist groups in Kosovo no longer exist."

Yugoslav army and Serbian police units launched a major offensive against the guerrillas in March, when NATO airstrikes began, and succeeded in overrunning the rebels' seven major command centers. Rebel attacks against the Serb-led forces have continued, although it is impossible to gauge their overall strength independently.

The Pristina Corps commanded by Lazarevic is the main Yugoslav Third Army unit permanently deployed in Kosovo and totals 11,000 troops. Lazarevic serves under Gen. Nebojsa Pavkovic, commander of the Third Army, who has an estimated 25,000 troops in the province.

The interview with Lazarevic took place on an open hillside. The distant roar of NATO jets competed with the shrill song of insects while the general's aides scanned the sky for planes. Lazarevic, bareheaded and in fatigues, appeared relaxed. He called Pentagon reports on KLA strength in Kosovo "dirty propaganda."

"If you think there are terrorists around us, 15,000 terrorists, is it possible to sit here enjoying natural beauty and talk for an hour with the only sound being NATO aviation and our own voices?" he asked. "Where are the terrorists being imagined on the pages of your newspaper? I could sit here all night and talk. I just don't have the time."

The stocky middle-aged officer said the KLA offensive across Mount Pastrik along the Albanian border with Kosovo was supported by Albanian army artillery. The Albanian army conducted what it said were live-fire exercises in the area on Thursday and again today.

Lazarevic said it was the second major effort by the Kosovo Liberation Army to force its way back into the war-ravaged province. The first attempt, on April 9, was launched from the Albanian town of Tropoje. He said that his troops also squelched that offensive and that Thursday's effort was "wider."

Lazarevic said his troops' battle with the KLA all but ended on May 9, when the Yugoslav high command announced a limited withdrawal from Kosovo.

In his view, NATO's support for the rebels undermines pledges by the alliance to disarm the group once Yugoslav forces withdraw. "If NATO wants to disarm the terrorist organization in Albania, that would be a good thing for stability in Albania and the region," he said.

"As for Kosovo-Metohija," he continued, using the name preferred by Serbian officials for the province, "this requires little comment. There are no terrorist forces. Individual disarmament [here], if any, will be done by security forces."

Lazarevic said NATO airstrikes in Kosovo have intensified in recent days; 200 bombs fell on Thursday alone. He said damage to military targets has been "minimal, really minimal, especially live targets."

"For us, military systems of all kinds and units are the highest priority, which we succeed in defending," he asserted.

He charged that NATO's stepped-up bombing was motivated by political, not military, considerations. The alliance wants to undermine peace efforts spearheaded by Russia's Balkans envoy, Viktor Chernomyrdin, Lazarevic said.

As he lounged on the grass, the general took pains to excuse the burning of houses and looting of ethnic Albanian shops in villages, towns and cities throughout Kosovo. The destruction of houses, he said, was the result of a "war situation" in which "some things get out of control."

CAPTION: Maj. Gen. Vladimir Lazarevic shown in an undated photo released by the State Department last month.