TEL AVIV (Reuters) - Pop superstar Madonna kicked off a new world tour on Thursday wishing peace on the Middle East even as she showcased grim dance routines depicting violence and bloody gunmen among her more colorful numbers.

Madonna, 53, mixed hit songs over three decades in music with tunes from her recent album, "MDNA," before a packed audience, and she took a sly dig at younger diva, Lady Gaga.

"She's not me!" Madonna belted out at the end of "Express Yourself," which she had reworked to include a sampling of Lady Gaga's recent "Born This Way."

That song from Lady Gaga, who emerged on the pop music scene about four years ago and has enjoyed a huge following, was noted by many fans and critics as being very similar to Madonna's late 1980s dance club smash.

Since Lady Gaga, 26, released "Born This Way," there has been speculation that a generational challenge was in the works and comedians have poked fun at any imagined rivalry between the two women.

Despite occasional lighthearted touches such as a baton-twirling routine in cheerleader formation and a psychedelic homage to Indian philosophy, the dominant mood at Thursday's concert in Tel Aviv seemed more grim with a stage shrouded in black and red and costumes that often appeared ominous.

VIRGIN SACRIFICE

"Like a Virgin," a dance tune that helped propel Madonna to stardom as risqué pop ingénue in the 1980s, was performed as a mournful cabaret with violin accompaniment. At one point, the singer was trussed up and hoisted into the air by four male dancers, then lowered onto a platform as though into a volcano - a virgin sacrifice.

For "Gang Bang," Madonna wrestled with armed intruders whom she then dispatched with a pistol - their "blood" spattering across an enormous video backdrop. In a routine for "Revolver", she wielded a Kalashnikov rifle, used by many modern-day insurgents, while one of her dancers favored an Israeli Uzi.

The exertions never sapped her confident singing, though she did become somewhat breathless during remarks to the audience at Ramat Gan stadium on Tel Aviv's outskirts.

"I chose to start my world tour in Israel for a very specific and important reason. As you know, the Middle East and all the conflicts that have been occurring here for thousands of years - they have to stop," she said to cheers.

A devotee of Jewish mysticism, Madonna had dubbed the first leg of her 28-country "MDNA" tour the "Peace Concert" and distributed free tickets to some of the Palestinians who attended from the occupied West Bank and east Jerusalem.

Among them was a woman named Yasmine, who declined to give her last name in light of Palestinian calls to boycott the Madonna concert and other cultural events in Israel. She offered a mixed assessment of the show.

"I wasn't a fan of the intro. It was too aggressive and massacre-like," Yasmine said. "Her (Madonna's) speech about peace and the mention of Palestine was heartfelt, though."

Avihay Asseraf, an Israeli who dedicated a Facebook page to Madonna's visit, was more sanguine about the darker displays.

"That's how she chose to express herself this time," he said. "Ultimately this is a show, a spectacle, and it's all for fun."